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Structural Diversity in Multicomponent Nanocrystal Superlattices Comprising Lead Halide Perovskite Nanocubes
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  • Ihor Cherniukh
    Ihor Cherniukh
    Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland
    Laboratory for Thin Films and Photovoltaics, Empa−Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
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    Orcidhttps://orcid.org/0000-0001-7155-5095
  • Taras V. Sekh
    Taras V. Sekh
    Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland
    Laboratory for Thin Films and Photovoltaics, Empa−Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
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  • Gabriele Rainò
    Gabriele Rainò
    Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland
    Laboratory for Thin Films and Photovoltaics, Empa−Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
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    Orcidhttps://orcid.org/0000-0002-2395-4937
  • Olivia J. Ashton
    Olivia J. Ashton
    Electron Microscopy Center, Empa−Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
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    Orcidhttps://orcid.org/0000-0002-0886-2110
  • Max Burian
    Max Burian
    Swiss Light Source, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
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    Orcidhttps://orcid.org/0000-0001-6728-6347
  • Alex Travesset
    Alex Travesset
    Department of Physics and Astronomy and Ames Laboratory, Iowa State University, Ames, Iowa 50011, United States
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    Orcidhttps://orcid.org/0000-0001-7030-9570
  • Modestos Athanasiou
    Modestos Athanasiou
    Experimental Condensed Matter Physics Laboratory, Department of Physics, University of Cyprus, 1678 Nicosia, Cyprus
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    Orcidhttps://orcid.org/0000-0003-1684-9482
  • Andreas Manoli
    Andreas Manoli
    Experimental Condensed Matter Physics Laboratory, Department of Physics, University of Cyprus, 1678 Nicosia, Cyprus
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  • Rohit Abraham John
    Rohit Abraham John
    Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland
    Laboratory for Thin Films and Photovoltaics, Empa−Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
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    Orcidhttps://orcid.org/0000-0002-1709-0386
  • Mariia Svyrydenko
    Mariia Svyrydenko
    Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland
    Laboratory for Thin Films and Photovoltaics, Empa−Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
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  • Viktoriia Morad
    Viktoriia Morad
    Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland
    Laboratory for Thin Films and Photovoltaics, Empa−Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
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  • Yevhen Shynkarenko
    Yevhen Shynkarenko
    Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland
    Laboratory for Thin Films and Photovoltaics, Empa−Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
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  • Federico Montanarella
    Federico Montanarella
    Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland
    Laboratory for Thin Films and Photovoltaics, Empa−Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
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    Orcidhttps://orcid.org/0000-0002-9057-7414
  • Denys Naumenko
    Denys Naumenko
    Institute of Inorganic Chemistry, Graz University of Technology, 8010 Graz, Austria
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  • Heinz Amenitsch
    Heinz Amenitsch
    Institute of Inorganic Chemistry, Graz University of Technology, 8010 Graz, Austria
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  • Grigorios Itskos
    Grigorios Itskos
    Experimental Condensed Matter Physics Laboratory, Department of Physics, University of Cyprus, 1678 Nicosia, Cyprus
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    Orcidhttps://orcid.org/0000-0003-3971-3801
  • Rainer F. Mahrt
    Rainer F. Mahrt
    IBM Research Europe−Zurich, CH-8803 Rüschlikon, Switzerland
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  • Thilo Stöferle
    Thilo Stöferle
    IBM Research Europe−Zurich, CH-8803 Rüschlikon, Switzerland
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  • Rolf Erni
    Rolf Erni
    Electron Microscopy Center, Empa−Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
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  • Maksym V. Kovalenko*
    Maksym V. Kovalenko
    Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland
    Laboratory for Thin Films and Photovoltaics, Empa−Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
    *Email: [email protected]
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    Orcidhttps://orcid.org/0000-0002-6396-8938
  • Maryna I. Bodnarchuk*
    Maryna I. Bodnarchuk
    Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland
    Laboratory for Thin Films and Photovoltaics, Empa−Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
    *Email: [email protected]
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    Orcidhttps://orcid.org/0000-0001-6597-3266
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ACS Nano

Cite this: ACS Nano 2022, 16, 5, 7210–7232
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https://doi.org/10.1021/acsnano.1c10702
Published April 6, 2022

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Abstract

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Nanocrystal (NC) self-assembly is a versatile platform for materials engineering at the mesoscale. The NC shape anisotropy leads to structures not observed with spherical NCs. This work presents a broad structural diversity in multicomponent, long-range ordered superlattices (SLs) comprising highly luminescent cubic CsPbBr3 NCs (and FAPbBr3 NCs) coassembled with the spherical, truncated cuboid, and disk-shaped NC building blocks. CsPbBr3 nanocubes combined with Fe3O4 or NaGdF4 spheres and truncated cuboid PbS NCs form binary SLs of six structure types with high packing density; namely, AB2, quasi-ternary ABO3, and ABO6 types as well as previously known NaCl, AlB2, and CuAu types. In these structures, nanocubes preserve orientational coherence. Combining nanocubes with large and thick NaGdF4 nanodisks results in the orthorhombic SL resembling CaC2 structure with pairs of CsPbBr3 NCs on one lattice site. Also, we implement two substrate-free methods of SL formation. Oil-in-oil templated assembly results in the formation of binary supraparticles. Self-assembly at the liquid–air interface from the drying solution cast over the glyceryl triacetate as subphase yields extended thin films of SLs. Collective electronic states arise at low temperatures from the dense, periodic packing of NCs, observed as sharp red-shifted bands at 6 K in the photoluminescence and absorption spectra and persisting up to 200 K.

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Assembly of monodisperse nanocrystals (NCs) into long-range ordered superlattices (SLs) makes an ideal platform for creating materials with controlled and programmed functionalities that result not only from the combination and enhancement of size-dependent properties of constituent building blocks but also from synergistic effects and emergent interactions between neighboring NCs. (1,2) Early examples include conductivity enhancement in binary SLs of Ag2Te with PbTe NCs, (3) exchange coupling effects in assemblies of magnetic NCs, (4) and near-field plasmonic-plasmonic resonance in the SL comprising gold NCs. (5) Various strategies have been developed for the fabrication of single and multicomponent SL structures with desired dimensionality and geometry, including colloid destabilization by nonsolvent diffusion, (6) drying-induced assembly over tilted substrate, (7,8) or at a liquid–air interface (9−11) and microemulsion-templated assembly. (12,13) Self-organization of NCs may be further governed by the external electric and magnetic fields. (14,15) The assembly of steric-stabilized colloidal NCs coated with hydrocarbon ligand chains relies on relatively weak (van der Waals, dipole–dipole, magnetic, Coulombic) interactions between NCs (1,16) with the considerable role of entropic contributions. (7) For example, the gain in free volume entropy upon self-assembly of monodisperse spherical NCs favors the formation of the densest possible structures with face-centered cubic (fcc) or hexagonal close packing. (1,17) For binary mixtures of spherical NCs, over 20 structures analogous to known atomic lattices were reported. Typically, the observed structure is the one having higher packing density (η) for a given NC size ratio, γ = dB/dA, where dB is the diameter of a smaller B-component and dA is the diameter of a larger A-component, both computed taking into account the dimensions of the core and ligand shell. (2,18−20) In the simple optimal packing model (OPM), (21) the effective diameter of steric-stabilized NCs is calculated assuming that the ligand shell is space-filling along the axis connecting neighboring NCs. Commonly observed are those binary SL structures, whose hard-particle packing densities are close to or exceed the packing density of fcc packing of spheres (η = 0.74).
Advancements in NC synthesis methodologies with exquisite NC size- and shape-engineering motivate the exploration of different SL structures. (22−24) The phase behavior of assemblies from shape-anisotropic NCs can be explained by the presence of directional entropic forces, which lead to dense local packing. (25) Already with single-component SLs of nonspherical NCs, minor differences in NC shape were reported to change the resulting structure; for instance, in the case of cubes vs truncated cubes such as Pt, PbS, or iron oxide. (26−29) A plethora of different binary SLs had been observed combining spherical NCs with several nonspherical NCs such as triangular nanoplates (columnar and three-dimensional structures), (18) nanowires and rhombic nanoplates (wherein chains of nanowires or stacked face-to-face plates template the assembly of spheres into ordered one-dimensional arrays), (30−32) nanorods (forming three-dimensional superstructures with the positional and orientational ordering of building blocks), (33,34) and branched octapod NCs. (35) Very little work has been reported for mixtures of exclusively nonspherical, anisotropic NCs. These are binary lamellar SL of shape-complementary nanoplates, (33) several columnar SLs from the mixtures of nanodisks and nanorods, (36,37) and, very recently, thin-film SLs from PbTe cubes coassembled with triangular nanoplates. (38)
Lead halide perovskite NCs─the latest generation of semiconductor quantum dots introduced in 2015 (39)─have attracted much attention for their enhanced properties as narrow-band, bright light emitters (40−42) and are intensely investigated for both classical light generation (light-emitting diodes, down-conversion in LCDs) (43,44) and as single-photon sources. (45,46) Being synthetically available as sharp, monodisperse cubes with edge-length tunable in 5–20 nm, (47−49) perovskite NCs are attractive highly uniform, shape-engineered building blocks for SLs. Since 2017, CsPbBr3 NCs had been reported to form superstructures with simple-cubic packing (scp). (50−57) At cryogenic temperatures, single-component CsPbBr3 NC SLs were found to exhibit superfluorescence. There, in contrast to spontaneous emission where the individual NCs emit photons randomly and independently, a coherent coupling among several NCs in superfluorescent domains leads to collective emission, resulting in ultrafast (few tens of picoseconds) bursts of photons. (53) These findings stimulated exploration of multicomponent SLs with perovskite NCs, as a means of attaining programmable positional and orientational order of these coherent light emitters. (58,59) Fundamentally important is that these were the original trials to coassemble cubic NCs with other shapes, and the outcome was vastly different from the results of the all-sphere NC self-assembly. Specifically, when CsPbBr3 nanocubes are coassembled with spherical dielectric NaGdF4 NCs, the binary perovskite b-ABO3-type SL forms, with cubes occupying B and O sites. Perovskite-type SL had not been reported, and not observed in our reference experiments, for all-sphere mixtures, which can be rationalized by much higher computed packing densities of this lattice when using cubes on B/O-sites. We then utilized the nonequivalence of B and O sites to incorporate the third component, truncated cubic PbS NCs, on a slightly larger B-site, yielding a ternary ABO3-type SL. (58) In the subsequent work, CsPbBr3 cubes were combined with thin LaF3 disks (1.6 nm in thickness, 6.5–28.4 nm in diameter), yielding six columnar structures, wherein columns of disks and cubes form a two-dimensional periodic pattern, and four three-dimensional structures that feature face-to-face contacts between cubes and disks of comparable size. (59)
Here, we present a detailed survey and comprehensive discussion of all multicomponent SL structures (Figure 1) obtained by combining cubic CsPbBr3 NCs (and FAPbBr3 NCs) with diverse spherical and nonspherical NCs into multicomponent SLs. Beyond refs (58and59), a broader selection of building blocks was utilized (truncated cuboids and thick disks), additional structure types are presented (AB2, b-ABO6, CaC2), and their formation was rationalized using space-filling calculations. Generally, cubic shape and facile ligand-deformability at the vertices and edges yield denser packing compared to spheres. In total, six structures were found in small cube-large sphere and small cube-large truncated cube mixtures, of which three are identical to those commonplace in all-sphere assemblies (NaCl, AlB2, and CuAu types) and the other three are exclusive to the use of cubes as smaller component (AB2, b-ABO3, b-ABO6). Unlike columnar structures with thin LaF3 disks, thick NaGdF4 nanodisks (18.5 nm thick, 31.5 nm in diameter) yield a CaC2-like lattice with clusters of two 8.6 nm cubes. In all presented structures, cubic NCs are orientationally locked. While the screening of SL formation in this work and in our earlier reports (refs (58and59)) were conducted by drying the colloids directly on the microscopy substrates, we also present the adaptation of the on-liquid formation of SLs as free-floating membranes for perovskite NCs, wherein a suited subphase solvent such as glyceryl triacetate is proposed. This polar solvent does not disperse apolar NC colloids drop-casted atop nor chemically damages the perovskite NCs. We also present the utility of the microemulsion-based method for the formation of multicomponent SLs comprising perovskite NCs. These SLs give rise to collective electronic states across perovskite NCs at low temperatures, as is evidenced by their photoluminescence (PL) and absorption spectra containing sharp red-shifted bands persisting up to 200 K.

Figure 1

Figure 1. Diversity of binary and ternary SLs obtained from 5.3 and 8.6 nm CsPbBr3 nanocubes combined with 11.2–25.1 nm spherical Fe3O4 and NaGdF4 NCs, 10.7–11.7 nm truncated cuboid PbS NCs, thick NaGdF4 disks (31.5 nm in diameter and 18.5 nm thick), and 6.5–28.4 nm disk-shaped LaF3 NCs. Structures in solid and dashed frames were obtained with 8.6 and 5.3 nm CsPbBr3 NCs, respectively. HAADF-STEM image illustrates a sharp shape of a CsPbBr3 nanocube. The graph is a space-filling analysis within a hard-particle model for NaCl-, AlB2-, and AB2- and within OTM for ABO3- and ABO6-type SLs comprising larger spherical and smaller cubic NCs; the dashed line corresponds to the density of fcc packing of spherical NCs.

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Results and Discussion

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Due to rather ionic bonding and specifics of surface termination with a high propensity of lead atoms to maintain octahedral coordination, perovskite NCs tend to expose nonreconstructed, CsBr-terminated facets [(100) in pseudocubic notation], essentially without truncation. (60) Sharp nanocubes CsPbBr3 with the edge lengths of 5.3 and 8.6 nm were synthesized by the hot-injection method (see respective luminescence and absorption spectra in Figure S1). (61,62) The NCs were coated by didodecyldimethylammonium bromide (DDAB), which is the shortest ligand still rendering these NCs colloidally stable. As manifested by the distinct diffraction arcs in the wide-angle selected-area electron diffraction (ED) pattern from the assembled monolayer (see Figure S2), nanocubes align face-to-face with the [001] zone axis parallel to the electron beam. CsPbBr3 nanocubes crystallize in orthorhombic Pnma structure with six facets terminated by four {101} and two {010} planes. (60) Since the d-spacing between {010} and {101} planes is nearly identical, in the ED analysis we treat the structure of CsPbBr3 NCs as pseudocubic with six facets terminated by {100} pseudocubic planes. 10.7 and 11.7 nm oleate-capped PbS nanocubes with truncated vertices possess rock-salt crystal structure and are terminated by {100} lattice planes. Due to similar PbS and CsPbBr3 lattice constants, their diffraction patterns overlap; however, because of the higher symmetry of the PbS structure, the {100} and {110} reflections are absent. The 11.2–25.1 nm Fe3O4 spherical NCs possessing inverse spinel cubic structure were synthesized by thermally decomposing iron oleate. (63) Spherical, 15.1–19.5 nm hexagonal-phase β-NaGdF4 NCs were synthesized by thermal decomposition of gadolinium trifluoroacetate. (31) Six arcs originating from {100} lattice planes imply slight hexagonal faceting of nanospheres. The decreased sodium-to-gadolinium ratio in the precursor solution and increased reaction time lead to NaGdF4 nanodisks (31.5 nm in diameter and 18.5 nm in thickness). The size distribution of NCs used in experiments was in the range from 2.9 to 7.7% [standard size deviation based on 200 particles, see transmission electron microscopy (TEM) characterization in Figure S2]. In most experiments, SLs were grown as polycrystalline films on a range of substrates (carbon-coated copper-grids and Si3N4 membranes on Si grids) by drying the NC mixtures in toluene.

Coassembly of CsPbBr3 Cubes with Spheres

First, we will discuss the systems of cubic 8.6 and 5.3 nm CsPbBr3 NCs with spherical Fe3O4 and NaGdF4 NCs. 8.6 nm CsPbBr3 nanocubes with spherical NCs can form NaCl-, AlB2- (along with AB2-), and b-ABO3-type SLs, depending on particle number ratio. Figure 2a shows NaCl-type SL obtained as a dominant product at a low CsPbBr3-to-NaGdF4 particle number ratio (ca. 1.2:1 and γ = 0.439). Wide-angle ED measured from a single SL domain reveals the orientation of CsPbBr3 cubes with ⟨100⟩ directions coinciding with ⟨100⟩SL, that is, each cube interacts with six spheres through flat facets; subscript “SL” denotes Miller indices of an SL. At high cube-to-sphere particle ratios (ca. 4.2:1), a b-ABO3-type SL is the sole product (Figure 3a–n). In this structure, spherical Fe3O4 or NaGdF4 NCs reside on the A site (1a position of Pm3̅m perovskite structure), while cubes occupy two crystallographically different sites, 1b (B site) and 3c (O sites). Distinct features of CsPbBr3 in the wide-angle ED reveal the orientation of O- and B-positioned cubes: CsPbBr3 NCs on faces (O-sites) interact with four spheres through facets and have two of ⟨110⟩ aligned with ⟨100⟩SL, while the cube in the center of the unit cell (B-site) is 45° rotated with respect to O-cubes and has all ⟨100⟩ aligned with ⟨100⟩SL (Figure 3c,m). Scanning electron microscopy (SEM, Figure 3d,n) and atomic force microscopy (AFM, Figure e–j) illustrate the surface topology of b-ABO3-type SLs. Precise height profile AFM measurement resolves two distinct surface terminations in [001]SL-oriented domains: (i) spheres terminated (Figure 3e–g) and (ii) B-site cubes terminated, as evident from sharper and higher maxima in Figure 3h–j.

Figure 2

Figure 2. Binary NaCl-type SL. (a) TEM image, (upper right inset) HAADF-STEM image, along with the corresponding (bottom inset) small-angle and (b) wide-angle ED patterns of a SL domain in [001]SL orientation assembled from 8.6 nm CsPbBr3 cubes and 18.6 nm NaGdF4 NCs. The upper left inset in (a) represents the NaCl-type unit cell according to the preferential cube’s orientation.

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Figure 3

Figure 3. Binary and ternary ABO3-type SLs. (a) TEM image along with (b) HAADF-STEM image, (c) the corresponding wide-angle ED pattern, and (d) SEM images of the [001]SL-oriented b-ABO3-type domains assembled from 8.6 nm CsPbBr3 cubes and 16.5 nm NaGdF4 spheres. (e, h) AFM height images of spheres- and cubes-terminated b-ABO3-type domains, respectively, along with (f, i) the height analysis of the profiles indicated in (e, h), (g, j) AFM three-dimensional images with the respective models. (k) TEM image along with (l) HAADF-STEM image, (m) the corresponding wide-angle ED pattern, and (n) SEM image of the [001]SL-oriented b-ABO3-type domains assembled from 8.6 nm CsPbBr3 cubes and 19.8 nm Fe3O4 spheres. (o) TEM image along with (p) HAADF-STEM image and (q) the corresponding wide-angle ED pattern of the [001]-oriented t-ABO3-type SL domains assembled from 8.6 nm CsPbBr3 cubes, 11.7 nm PbS truncated cuboids, and 21.5 nm Fe3O4 spheres. (r) HAADF-STEM image of a t-ABO3-type SL domain in [111]SL orientation assembled from 8.6 nm CsPbBr3, 11.7 nm PbS, and 25.1 nm Fe3O4 NCs; upper inset shows the model of [111]SL-oriented t-ABO3 unit cell, and lower inset shows small-angle ED pattern. Insets in (a, k, o) represent binary and ternary ABO3-type lattices according to the preferential NCs orientations, with Fe3O4 shown as gray spheres, NaGdF4 as yellowish spheres, CsPbBr3 as blue cubes, and PbS as red truncated cubes. The origin of wide-angle ED reflections in (c, m, q) is color-coded to match the NCs in insets.

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The formation of NaCl and b-ABO3 SLs with cubic NCs can be rationalized by their high packing densities, exceeding those of fcc packing of spheres (Figure 1). (58) The coordination environment of B- and O-positioned cubes in b-ABO3-type structure is different, for example, at γ ≥ 0.414, O-cubes interact through vertices, while B-cubes are rattlers. Targeted incorporation of larger (compared to perovskite cubes) truncated cuboidal PbS NCs (11.7 nm) on B-sites leads to a three-component t-ABO3-type SL with higher packing density than that of b-ABO3 lattice comprising the same sizes of spheres (21.5 and 25.1 nm) and perovskite cubes (8.6 nm), Figure 3o–r. Wide-angle ED confirms the same orientation of O-site perovskite cubes as in the binary lattice, and PbS truncated cubes preserving the orientation of B-site perovskite cube. The PbS incorporation into the structure is apparent from high contrast in high-angle annular dark-field scanning TEM (HAADF-STEM) images (Figure 3p,r). The completeness of the substitution of CsPbBr3 cubes on B site by PbS NCs is evident from the absence of (110) reflection (“1” in Figure 3q) expected from the center perovskite cube, while the (220) reflection originating from PbS (“2” in Figure 3q) is intensely diffracting in the analogous direction. These structures are also described in our previous work, ref (58).
At the intermediate particle number ratios (ca. 2.2:1, cubes-to-spheres), the dominant product is an AlB2-type SL. Figure 4a–e shows TEM characterization of [120]SL-oriented domain assembled from 8.6 nm CsPbBr3 and 19.8 nm Fe3O4 NCs, while Figure 4f–j presents [001]SL-oriented domain obtained from 8.6 nm CsPbBr3 combined with 16.5 nm NaGdF4 NCs. In this lattice, nanocubes occupy each trigonal prismatic void in a simple hexagonal lattice of spheres. Wide-angle ED pattern from [120]SL-oriented domain (Figure 4e) comprises narrow arcs originating from (110) and (111) CsPbBr3 lattice planes that run in perpendicular directions, while the ED pattern from [001]SL projection (Figure 4j) features six (110) CsPbBr3 arcs at 60° angles. This is reflective of the preferential orientation of CsPbBr3 nanocubes in the SL: one of their [111] directions is aligned with [001]SL (6-fold axis) and [110] with [010]SL, that is, cubes interact with three spheres from one side of the trigonal prismatic void via facets and with three spheres from another side via edges.

Figure 4

Figure 4. Binary AlB2-type SLs obtained combining 8.6 nm CsPbBr3 with (a–e) 19.8 nm Fe3O4 and (f–j) 16.5 nm NaGdF4 NCs. (a, b) TEM and (c) HAADF-STEM images of a single domain in [120]SL orientation, along with the corresponding (d) small-angle and (e) wide-angle ED patterns. (f, g) TEM and (h) HAADF-STEM images of a single domain in [001]SL orientation, along with the corresponding (i) small-angle and (j) wide-angle ED patterns. Insets in (e, j) show the orientations of CsPbBr3 NCs in the SL domains with respect to the electron beam (normal to the image plane).

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Smaller, 5.3 nm CsPbBr3 nanocubes with Fe3O4 NCs readily form NaCl- (Figure S3) and AlB2-type SLs, in which, similar to larger cubes, a high degree of orientational order is observed. AlB2-type binary SLs are obtained with iron oxide NCs (11.2–15.6 nm, γ = 0.443, 0.405, 0.368, 0.336, Figure 5 and Figure S4). Structural peculiarities of the AlB2 binary SL are detailed here for the case of 12.5 nm Fe3O4 NCs (Figure 5). The grazing-incidence small-angle X-ray scattering (GISAXS) pattern shows strong, periodic reflections (Figure 5c) owing to long-range order and complex, base-centered orthorhombic symmetry (C222), resulting from the stacking of hexagonal CsPbBr3 and Fe3O4 layers, with an in-plane A–B–A–B packing direction, as also confirmed by energy-dispersive X-ray spectroscopy (EDX-STEM, on Figure 5g). See Supplementary Note 1 and Figure S5 for further details on GISAXS SL characterization. TEM tilting series readily differentiate the predominantly observed [120]SL projection of the AlB2-type from the similar [100]SL projection of CuAu-type SL (Figure S6). The AlB2-type structure was additionally confirmed by electron tomography of [001]SL-oriented domain (see Supplementary Video 1). Figure 5i–n displays occasionally observed [001]SL and [010]SL projections of AlB2-type SL. The signal-to-noise ratio was improved upon template matching and averaging of large homogeneous areas of TEM images (insets in Figure 5i,l). Small-angle ED and wide-angle ED patterns (for [120]SL-orientation) confirm the preferential orientation of nanocubes analogously to AlB2-lattices with larger CsPbBr3 NCs, albeit with much weaker intensities of perovskite reflections due to reduced scattering factor of small NCs. The broader arcs indicate a higher orientational freedom of smaller nanocubes within the SL. The (111) and (110) lattice planes of CsPbBr3 are normal to [001]SL and [010]SL, respectively, as in the binary SLs with larger cubes. However, there are three sets of {110} CsPbBr3 lattice planes with a common [111] zone axis that is parallel to [001]SL. Therefore, 60° rotation around [001]SL does not change the position of diffraction spots. Consequently, there are two possible relative orientations of nanocubes: half of the cubes being 60° rotated about [001]SL (“O1”) or all having the same orientation (“O2”, Figure 6a). We would also note that ambiguity in this rotational orientation around [001]SL, as well as the possibility of the partial rattling of cubes along the same direction (not resolvable with TEM images), complicates the packing density analysis (Figure 6b). Our analysis shows that a combined effect of the “O2”-orientation and cube displacement along [001]SL direction can lead to the hard-particle packing densities of 0.7–0.8 in the γ range of 0.35–0.70 (see detailed discussion and calculations in the Supplementary Note 2).

Figure 5

Figure 5. Structural characterization of a binary AlB2-type SL comprising 5.3 nm CsPbBr3 and 12.5 nm Fe3O4 NCs. (a) TEM image of [120]SL-oriented domain; inset is the image at higher magnification. (b) Wide-angle ED pattern of a single SL domain in (a). (c) Two-dimensional GISAX scattering pattern, showing long-range order in AlB2-type binary domains. (d) The unit cell of AlB2-type SL. (e) Small-angle ED pattern of a domain shown in (a). (f) HAADF-STEM image of the [120]SL-oriented domain. (g) EDX-STEM maps for Fe (gray, K-line) and Pb (blue, L-line) of the [120]SL-oriented domain. (h, k, n) Crystallographic models of [120]SL, [001]SL, and [010]SL-oriented AlB2 lattice, respectively. (i, j) Low- and high-magnification TEM images of an [001]SL-oriented domain. (l, m) Low- and high-magnification TEM images of a [010]SL-oriented domain; insets in (i, l) are images obtained by template-matching analysis of corresponding TEM images.

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Figure 6

Figure 6. Possible relative orientations of CsPbBr3 nanocubes within AlB2-type SL and packing fractions predicted by OPM packing analysis according to the hard-particle model. In both orientations, the body-diagonal of the cubes is parallel to the c-axis of the hexagonal SL unit cell, that is, [001]SL. In orientation “O1”, the cubes are mutually rotated by 60°, whereas in orientation “O2”, they are identically aligned. A significant increase in the packing fraction can be achieved if the B-cubes in orientation “O2” are not locked in the 2d Wyckoff positions, that is, are allowed to slide along the [001]SL (“O2 S3”). Wide-angle ED patterns from [120]SL- (see, for instance, Figures 4e and 5b) and [001]SL-oriented domains (Figure 5j) point to the alignment of all cubes with one body diagonal parallel to [001]SL and (110) CsPbBr3 planes are orthogonal to [010]SL. Hence these two orientations can be proposed. Experimentally, however, there exists no evidence to differentiate between these two structures, and hence both were considered for the analysis of lattice parameters and packing densities. Excluded is also a substantial orientational disorder in any dimension.

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Next to AlB2-type binary SLs and for both sizes of nanocubes combined with Fe3O4 spheres, another AB2 structure belonging to the tetragonal crystal system, namely the P42/mmc space group, concomitantly forms (Figure 7 and Figures S8−S10). This structure can be viewed as derived from the AlB2 structure with a small modification: Shifting of each fourth (100) lattice plane along [011] vector, the corresponding lattice plane and the direction of shifting are marked in Figure 7d. This AB2-type packing is characterized by spherical NCs forming trigonal prisms, highlighted in Figure 7d, alternating in two perpendicular directions normal to the out-of-plane [001]SL, with cubic NCs occupying each void orienting in the same way as in the trigonal prismatic void of AlB2-type lattice, hence retaining the AB2 stoichiometry. Such ordering is in agreement with the contrast differences in TEM, HAADF-STEM images, EDX elemental mapping, and wide-angle ED patterns of [001]SL projection (Figure 7 and Figures S9 and S10). Its wide-angle ED displays reflections originating from (110) and (111) CsPbBr3 lattice planes (four arcs of each kind) running normal to [100]SL and [010]SL, which implies two relative orientations of nanocubes with a 90° angle between [111] directions because reflections from (110) and (111) planes of one nanocube cannot appear in the same direction. The higher yield of AlB2-type SLs indicates its lower formation energy barrier compared to AB2 SLs, while the calculated packing densities of both structures coincide up to γ ≤ 0.435 (see for details Supplementary Note 3 and Figure 1 and Figure S8).

Figure 7

Figure 7. An AB2-type binary SL assembled from CsPbBr3 nanocubes and Fe3O4 nanospheres. (a) TEM image of a SL assembled by 8.6 nm CsPbBr3 and 19.8 nm Fe3O4 NCs (γ = 0.414), along with the corresponding (inset) small-angle ED pattern, (b) HAADF-STEM image, and (c) wide-angle ED pattern. (d) Comparison of AlB2 (taken as orientation “O2”, see Figure 6) and AB2 structures. Red and green lines show the normals to (111) and (110) CsPbBr3 lattice planes, respectively, and indicate the directions of reflections in wide-angle ED patterns. (e) HAADF-STEM image showing grain boundary between AlB2 and AB2 binary SL domains. (f) Modeled crystallographic projections of cubic and spherical NCs in AB2 structure. (g) EDX-STEM elemental maps of an AB2-type binary SL assembled from 5.3 nm CsPbBr3 and 14.5 nm Fe3O4 NCs for Pb (blue, L-line) and Fe (red, K-line).

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At γ = 0.315 (5.3 nm CsPbBr3 and 16.9 nm Fe3O4 NCs) and high cube-to-sphere particle number ratio (ca. 12:1), binary b-ABO6-type SL forms (Figure 8). It possesses a Pm3̅m space group with cubic NCs occupying one B-site (1b Wyckoff position) and six O-sites (6f Wyckoff position). This structure can also be viewed as ABO3-like, where each of three O-sites (3c Wyckoff position) are occupied by two small cubes. O-positioned cubes are well resolved in HAADF-STEM images of [111]SL-, [101]SL-, and, especially, [001]SL-oriented domains (Figure 8d–g). Higher intensity of four {110} CsPbBr3 arcs in the wide-angle ED is in agreement with the alignment of the majority of cubes (O-sites) with two of ⟨110⟩ crystallographic directions pointing along with two ⟨100⟩SL; however, their broadening may indicate lower orientational order. Space-filling analysis within the hard-particle model revealed a narrow maximum which is still below the fcc limit (Figure 8b). Consideration of the deformability of ligand shell on cubic NCs contacting through vertices, within orbifold topological model (64) (OTM, see calculations in the Supplementary Note 4), results in the densification of the lattice and may explain its formation within a narrow size ratio range as such lattice was not observed with 19.8 and 15.6 nm Fe3O4 NCs.

Figure 8

Figure 8. Binary ABO6-type SLs obtained from 5.3 nm CsPbBr3 and 16.9 nm Fe3O4 NCs (γ = 0.315). (a) Wide-angle and (inset) small-angle ED patterns of [001]SL-oriented domain. (b) Space-filling analysis for b-ABO6-type SLs comprising larger spherical and smaller cubic (solid line) or spherical (blue dashed line) NCs within the hard-particle model, except for the indicated OTM branch. (c) Structural model of a b-ABO6-type unit cell and a slice through (002)SL. (d–f) HAADF-STEM images of [001]SL-, [111]SL-, and [101]SL-oriented domains and (g) the corresponding structural models of SL projections.

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The usage of 15.2 nm NaGdF4 NCs as spherical building blocks in coassembly with 5.3 nm CsPbBr3 nanocubes (γ = 0.344) results in the formation of NaCl-, AlB2-, and AB2-type SLs with orientationally aligned perovskite nanocubes (Figure 9a–l), analogously to the case of Fe3O4 spheres. We also observed the formation of b-ABO3-type SL at a high cube-to-sphere particle number ratio in the solution (Figure 9m,n). Interestingly, as evident from distinct arcs in wide-angle ED, a high degree of orientational ordering of A-site NCs was observed in all these structures, especially in AlB2- and AB2-types featuring hexagonal motifs, further pointing to the hexagonal faceting of NaGdF4 NCs. Specifically, in NaCl-type SL, the (100) lattice planes tend to align normally to the in-plane ⟨110⟩SL. At γ < 0.414, NaCl-type SL is defined by the fcc sublattice of A-particles with cubes rattling in the voids and neighboring NaGdF4 NCs prefer to interact through the surfaces faceted by (100) and (001) planes. Interestingly, at γ > 0.414 (see Figure 2a,b for γ = 0.439), when A-particles contact O-cubes, the preferred orientation of NaGdF4 NCs is different, they orient faceted surfaces toward cube facets, as manifested by a higher intensity of (100) and (002) wide-angle ED reflections along ⟨100⟩SL. In AlB2-type SL, NaGdF4 NCs within one hexagonal layer contact each other predominantly through the surfaces terminated by (100) planes and contact A-particles from other layers by (001) terminated surfaces, as is evident from six sharp (100) diffraction spots measured from [001]SL-oriented domain and from the sets of (100) and (002) narrow arcs originating along [010]SL and [001]SL directions, respectively, measured from [120]SL-oriented domain (Figure 9f,h). The wide-angle ED pattern measured from [001]SL-oriented AB2-type domain (Figure 9j) consists of two sets of the NaGdF4 reflections present in the pattern of [120]SL-oriented AlB2-type domain (Figure 9h) rotated by 90°, completely in agreement with the proposed AB2 structure in Figures 7d and 9o. The formation of b-ABO3-type SL can benefit from the patchiness of NaGdF4 NCs, (65) as in this structure, which at γ < 0.414 is governed by contacts between A-particles in scp, NaGdF4 NCs orient their surfaces faceted by (100) and (001) planes along [100]SL and [110]SL in-plane directions.

Figure 9

Figure 9. Binary SLs self-assembled from the mixtures of 5.3 nm CsPbBr3 and 15.2 nm NaGdF4 NCs. Increasing the relative concentration of CsPbBr3 NCs changes the experiment outcome from (a–d) NaCl-type to (e–h) AlB2-type with (i–l) AB2-type and then to (m, n) ABO3-type SLs, as illustrated by (o) the scheme. (a, e, i, m) TEM images of [001]SL projections, along with the corresponding (bottom insets) small-angle ED and (b, f, j, n) wide-angle ED patterns; the respective high-magnification HAADF-STEM images are shown as upper insets. (c, d) HAADF images of [001]SL- and [111]SL-oriented domains. (g) TEM image of [120]SL-oriented domain, along with the corresponding (upper inset) HAADF-STEM image, (bottom inset) small-angle ED, and (h) wide-angle ED patterns. (k) Bright-field and (l) HAADF-STEM images of [001]SL-oriented domain.

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Coassembly of CsPbBr3 Cubes with Truncated Cuboids

We then studied the assembly behavior of the system comprising CsPbBr3 cubes and truncated cuboid PbS NCs. Intriguingly, truncated cubes can behave similarly to spheres and occupy A-sites in binary ABO3- and NaCl-type SLs, albeit losing orientational freedom. The b-ABO3-type SLs form from the mixtures of 8.6 nm CsPbBr3 nanocubes with 10.7–11.7 nm truncated cubic PbS NCs (Figure 10). The corresponding size ratios (γ = 0.72–0.78) are much higher compared to the systems with spherical NCs as an A-component wherein b-ABO3-type SL forms up to γ = 0.54. EDX-STEM maps confirm that PbS NCs occupy only A-sites. Eight (100) and (110) maxima which appear in the directions normal to ⟨100⟩SL and ⟨110⟩SL together with eight (111) maxima with a splitting angle of 19.5° in wide-angle ED pattern indicate the presence of B- and O-positioned CsPbBr3 cubes with the same orientations as in the b-ABO3-type SLs comprising spheres on A-sites. Moreover, as can be seen from TEM image and wide-angle ED analysis, namely the higher intensity of the reflections “2” and “3” which originate mainly from strongly diffracting PbS NCs compared to the intensity of the reflections “1” and “4” which are produced only by CsPbBr3 NCs, the orientation of PbS NCs is not random and matches the orientation of O-site CsPbBr3 nanocubes residing on the unit cell faces parallel to the substrate. Such PbS orientation implies contacts between PbS vertices and faces of the other O-site cubes residing on perpendicular to the substrate facets of ABO3 lattice (see insets in Figure 10a,d), making the truncated shape of larger cubes beneficial for the formation of b-ABO3 structure. For example, such a structure could not be obtained from the binary mixtures of sharp cubic CsPbBr3 NCs of two sizes.

Figure 10

Figure 10. Characterization of b-ABO3-type SL assembled from 8.6 nm CsPbBr3 and 10.7–11.7 nm PbS. (a) HAADF-STEM image of a single [001]SL-oriented binary ABO3 domain comprising of 8.6 nm CsPbBr3 NCs and 11.7 nm PbS NCs. (b) TEM image of a single b-ABO3 domain in [001]SL orientation assembled from 8.6 nm CsPbBr3 NCs and 10.7 nm PbS NCs, together with the respective (c) small-angle and (d) wide-angle ED patterns. Diffraction arcs are colored to show their origin from CsPbBr3 and PbS NCs presented as insets. Inset in (a) shows the binary ABO3 lattice and illustrates the relative position and orientation of NCs. (e) Crystallographic model of a [001]SL-oriented ABO3 lattice, along with HAADF-STEM image and respective EDX-STEM maps for S (red, K-line), Pb (blue, L-line), Cs (green, L-line), and Br (yellow, K-line).

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At lower CsPbBr3 loading, the dominant product is NaCl-type SL which is characterized by the alignment of ⟨100⟩ directions of both CsPbBr3 and PbS NCs coinciding with ⟨100⟩SL, as is evident from ED. Figure 11a–c shows TEM and HAADF-STEM images of binary domains with gradually increasing thickness, in agreement with the vanishing difference in intensities of neighboring SL site projections of NaCl-type SL. A much higher wide-angle ED intensity of (200) and (220) peaks compared to that of (100) and (110) results from stronger scattering on PbS lattice planes, which contribute only to the former set of reflections and do not to the latter due to higher Fm3̅m symmetry of the PbS lattice; furthermore, (200) and (220) reflections from PbS and CsPbBr3 add up due to similar lattice constants (Figure 11g and Figure S11).

Figure 11

Figure 11. NaCl-type binary SLs from 8.6 nm CsPbBr3 NCs combined with truncated cuboid PbS NCs. (a) TEM image of a monolayer domain. (b, c) HAADF-STEM images of SL domains with an increasing number of layers. (e, f) TEM images of [001]SL-oriented SL domains at different magnification, along with the (g) wide-angle and (h) small-angle ED patterns measured from the domain shown in (f); the reflections from CsPbBr3 and PbS NCs are colored to match the NCs in the structural model (d). Images from (a, c, f–h) were obtained with 10.7 nm PbS NCs (γ = 0.778) and from (b, e) with 11.7 nm PbS NCs (γ = 0.720).

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The 8.6 nm CsPbBr3 cubes with 10.7 nm PbS truncated cubes also form a CuAu-type SL (Figure 12a–f). Typically observed is the [101]SL orientation (Figure 12a). The site occupancies are confirmed by recording HAADF-STEM images of [101]SL-oriented domains at 0° and 45° tilting angles and comparing them with the modeled CuAu projections (Figure 12d,e). Complex wide-angle ED pattern (Figure 12b), contrary to b-ABO3- and NaCl-type SLs, reveals several different orientations of PbS cuboids that reside on equivalent lattice sites. Similar orientational behavior of PbS NCs is observed in AlB2-type SL assembled from 5.3 nm CsPbBr3 NCs (Figure 12g–i). The [010]SL and [001]SL orientations that are common to AlB2-type SLs from all-sphere systems were observed (Figure 12g), while the dominant one was [120]SL. In this lattice, the majority of PbS NCs are aligned with [110] along [120]SL and [100] along [010]SL; however, several distinct peaks remain undefined. Weak CsPbBr3 (110) arcs indicate that perovskite cubes orient one edge along [010]SL, yet the intense (111) reflections from PbS NCs hinder the determination of CsPbBr3 (111) peaks, and, consequently, the conclusion whether cube orientation is the same as in the AlB2-type SL with spherical NCs on the A-site.

Figure 12

Figure 12. CuAu- and AlB2-type binary SLs assembled from truncated cuboid 10.7 nm PbS NCs and, respectively, 8.6 and 5.3 nm CsPbBr3 cubes. (a) TEM image of a single CuAu-type SL domain in [101]SL orientation, along with the corresponding (inset) small-angle ED and (b) wide-angle ED patterns (the origin of the reflections is color-coded to match the NCs in the model shown as inset). (c) CuAu unit cell and crystallographic model of [101]SL-oriented lattice assuming preferable orientations of NCs in agreement with ED. (d) HAADF-STEM images of a SL domain taken at 0° and 45° tilting angles around [010]SL that correspond to [101]SL and [001]SL orientations, respectively; crystallographic model of [001]SL-oriented CuAu-type lattice is depicted in the inset of (e). (f) EDX-STEM elemental maps recorded from a [001]SL-oriented domain shown in (e). (g) TEM image of AlB2-type SL with twist grain boundaries between [001]SL- (magnified in upper inset) and [010]SL-oriented (magnified in bottom inset) domains. (h) HAADF-STEM, high-magnification TEM image (upper inset), and crystallographic model (bottom inset) along with (i) wide-angle ED pattern of [120]SL-oriented AlB2-type SL. Bottom and upper ([120]SL orientation) insets in (i) represent the unit cell of AlB2-type SL with orientations of NCs that result in the most intense wide-angle ED spots marked in red (PbS) and blue (CsPbBr3).

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Coassembly of CsPbBr3 Cubes with Thick Nanodisks

Combining 8.6 nm perovskite nanocubes with larger NaGdF4 disks (31.5 nm in diameter and 18.5 nm in thickness) resulted in the formation of an SL structure featuring the periodic clustering of two CsPbBr3 NCs, which we interpret as a CaC2-like SL (Figure 13), albeit with an orthogonal unit cell metric due to anisotropic shape of the NaGdF4 NCs. SEM images of the surface of SL domains (Figure 13d,e) show the occupancy of one lattice site by pairs of cubes with face-to-face alignment. Within one layer, cubes are surrounded by four vertically oriented disks, two of which approach cubes by flat faces and the other two by their rims. Nanodisks from the next layer assemble on top of cubes from the previous layer, emulating the CaC2-like packing. Such ordering is in agreement with the contrast observed in TEM of the monolayer domain (Figure S12) and TEM and HAADF-STEM image of multilayer (Figure 13a,b) and was unambiguously confirmed by electron tomography reconstruction of ordered SL domains (see Supplementary Video 2). Four narrow arcs from (100) and (110) CsPbBr3 lattice planes in the wide-angle ED reveal the orientation of perovskite cubes, pointing their faces along three lattice vectors (Figure 13c). However, the more pronounced (100) peak along the shortest lattice vector may indicate some tilt of the cubes around this direction.

Figure 13

Figure 13. CaC2-like SL assembled from 8.6 nm CsPbBr3 nanocubes and 31.5 nm NaGdF4 thick nanodisks, featuring sets of two cubes on one lattice site. (a) TEM image and the SL models are shown as insets. (b) HAADF-STEM images at different magnifications, along with the corresponding (c) wide-angle ED and (inset) small-angle ED patterns. (d, e) SEM images at different magnifications.

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Multicomponent SLs Comprising FAPbBr3 Nanocubes

Apart from cuboid CsPbBr3 NCs, also hybrid organic–inorganic perovskite NCs, namely formamidinium lead bromide (FAPbBr3) NCs can serve as versatile building blocks for NC SLs. For example, 9 nm FAPbBr3 cubes with larger spherical 15.1–19.5 nm NaGdF4 NCs form b-ABO3-, AlB2-, and AB2-type structures (Figure 14a–c). The 5.7 nm FAPbBr3 nanocubes, in analogy to 5.3 nm CsPbBr3 NCs, (58,59) form the NaCl-type SL with 15.1 nm NaGdF4 spheres (Figure 14d) and columnar AB-type or lamellar (which is the dominant product) SLs with 12.5 nm LaF3 nanodisks (Figure 14e–g).

Figure 14

Figure 14. Binary SLs obtained from FAPbBr3 nanocubes. (a) TEM and HAADF-STEM (top right panel) images of a b-ABO3-type SL assembled from 9 nm FAPbBr3 and 19.5 nm NaGdF4 NCs; SL model is shown in the bottom right panel. (b, c) Bright-field STEM images of, respectively, an [120]-oriented AlB2-type and [001]SL-oriented AB2-type SL domains comprising 9 nm FAPbBr3 and 15.1 nm NaGdF4 NCs. (d) HAADF-STEM image of an [111]-oriented NaCl-type SL domain comprising 5.7 nm FAPbBr3 and 15.1 nm NaGdF4 NCs. (e) Bright-field STEM image of a columnar AB-type SL domain obtained from 5.7 nm FAPbBr3 NCs and 12.5 nm LaF3 nanodisks. (f) TEM and (g) HAADF-STEM images of lamellar SL obtained from 5.7 nm FAPbBr3 NCs and 12.5 nm LaF3 nanodisks; EDX-STEM elemental maps for La (magenta, L-line) and Pb (blue, L-line) are shown in the inset in (g). Insets in (b–d) are SL models.

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Self-assembly of Perovskite NCs on Liquid Subphase

Thus, far, the presented SLs were obtained by casting the small volume of the mixture of NCs (ca. 28–35 μL in toluene) over the substrates located in the tilted vial. This simple approach allows for facile screening of the SL formation yet has its drawbacks too. For instance, the range of suitable substrates is rather limited to hydrophobic surfaces. The obtained films usually are characterized by cracks between SL domains that reduce surface coverage. Moreover, adhesion of the SL domain to the substrate, while it still contains solvent, may result in additional crack formation within the domain. (20) Drying-mediated assembly on the surface of an immiscible liquid, usually a polar solvent such as ethylene glycols and acetonitrile, used as support was introduced to overcome these issues, allows for obtaining centimeter-scale SL membranes transferable to the arbitrary substrate, enabling integration of thin-film SLs into devices. (9) This method is, however, difficult to extend to perovskite NCs as even a small but finite solubility in the subphase polar solvent compromises their structural integrity.
After the extensive screening of possible alternatives, we find that glyceryl triacetate is both immiscible with nonpolar solvents such as toluene and hydrocarbons and also does not disperse or chemically harm perovskite NCs and can be utilized as a support in the liquid–air interfacial assembly (see Figure 15a). We also note that fluorinated solvents, such as FC-40, satisfy the aforementioned requirements, but the nonpolar solvents have a low tendency to spread into a needed thin liquid layer on this fluorinated subphase due to limited wettability. Noteworthy, perfluorodecalin featuring partial miscibility with hexane was successfully used as a substrate for obtaining three-dimensional nearly isotropic perovskite SLs. (54) The self-assembly on glyceryl triacetate occurs within several minutes to several hours depending upon solvent evaporation rate (hexane, octane, decane, or dodecane). Figure 15b–d shows an extended monolayer of CsPbBr3 NCs assembled on the surface of glyceryl triacetate from the solution of NCs in octane. Mixtures of NCs yield ordered binary mono- and multilayers with different structures depending on the concentration, particle number, and size ratios (Figure 15e–g).

Figure 15

Figure 15. Self-assembly of perovskite NCs at the liquid–air interface. (a) Illustration of the assembly process: NCs dispersed in nonpolar solvents are cast onto the surface of glyceryl triacetate in a Teflon well or Petri dish, which is then covered with glass or larger Petri dish, respectively; ordered SL film floating on the subphase is formed upon evaporation the solvent. (b–d) TEM images of 9 nm CsPbBr3 NC monolayer obtained from octane on glyceryl triacetate. (e–g) TEM images of AB-type monolayer (obtained from dodecane) and NaCl- and AlB2-type films (obtained from decane), respectively, comprising 8.6 nm CsPbBr3 and 19.8 nm Fe3O4 NCs.

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Self-Assembly of Binary Supraparticles Comprising Perovskite NCs

Microemulsion-templated self-assembly is another method enabling the control over the superstructure dimensionality and allows for the formation of three-dimensional supraparticles upon the assembly in spherical confinement of the “oil” droplet (colloid) stabilized in an immiscible solvent with the aid of a surfactant. (66,67) Potentially, such ordered multicomponent supraparticles can serve as building blocks for mesoscale materials with hierarchical order, wherein the properties could be defined by constituent NCs, their packing within the supraparticles, and finally by the ordering of supraparticles themselves. Furthermore, dispersed individual supraparticles can be, in principle, manipulated and deposited on-demand into desired locations within photonic and other structures. Colloidal spheres of mono- and binary SLs were reported to form from the emulsions of nonpolar solvents in water. (12,68,69) Recently, a carrier solvent–surfactant pair suitable for dispersing perovskite NC colloidal droplets (in toluene) was developed, namely, fluorinated solvents FC-40 or HFE-750 and fluorinated surfactant 008-FS, yielding single-component perovskite supraparticles. (70) Here, we extend the method to binary SLs with perovskite NCs (Figure 16). Supraparticles with b-ABO3-type structures can be obtained from the emulsions of 8.6 nm CsPbBr3 and 18.6 nm NaGdF4 NCs (Figure 16b). Smaller domains appear to be single crystalline, albeit, as revealed by electron tomography reconstruction (71) (see Supplementary Video 3), they may possess structural defects such as nanocube vacancies. The growth inside larger droplets leads to 500–1500 nm supraparticles and is characterized by several nucleation sites resulting in polycrystalline SLs (72) (see SEM images in Figure 16b). Perovskite cubes with thick NaGdF4 disks form supraparticles with the ordering analogous to the CaC2-like structure (Figure 16c) presented earlier (Figure 13).

Figure 16

Figure 16. Oil-in-oil templated assembly of binary SLs comprising perovskite NCs. (a) Illustration of the assembly process: NCs dispersed in toluene are mixed with a fluorinated solvent (FC-40) containing surfactant (008-FS) that is capable of stabilizing droplets with NCs. Slow evaporation of toluene from the droplets during stirring results in the formation of ordered binary supraparticles. (b) SEM and HAADF-STEM (right panel) images of supraparticles with b-ABO3 structure obtained from 8.6 nm CsPbBr3 cubic and 18.6 nm NaGdF4 spherical NCs. (c) SEM images of supraparticles with CaC2-like structure assembled from 8.6 nm CsPbBr3 nanocubes and 31.5 nm NaGdF4 thick nanodisks. Insets in (b, c) show the SL models.

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Collective Optical Properties of b-ABO3 and AlB2-type SLs

An exceptional emissivity of lead halide perovskite NCs motivates the exploration of their properties at both single-particle and ensemble levels. Here, we focus on the optical properties where, already on the single-NC level, perovskite NCs are standing out because of their exceptionally fast radiative rates and high oscillator strength (73) and long exciton coherence. (45,74) Scalable self-assembly from colloids makes for an attractive path to the controlled aggregate states of these bright emitters. The relationship between the periodic mesostructure and emerging collective luminescent characteristics can then be delineated and rationalized. Collective PL properties had been observed in our earlier work on monocomponent CsPbBr3 NC SLs (53) and binary ABO3-type SLs (CsPbBr3 cubes + NaGdF4 spheres), (58) studied at cryogenic temperatures. Already with cw-excitation, coupling between perovskite NCs is apparent from the sharp PL band, red-shifted with respect to the excitonic PL of uncoupled NCs. Furthermore, for the same samples, pulsed excitation with higher fluencies gives rise to superradiant emission, specifically superfluorescence. Superfluorescence emerges when coherence is established over a number of excited emitters via a common radiation field, forming a giant dipole. This then manifests itself as short (subnanosecond) and intense (proportional to the squared number of coupled emitters) bursts of light.
Herein, we survey the behavior of the red-shifted PL band, as well as concomitant absorption band, from the coupled NCs in relation to the lattice structure and NC size and composition. Such energetically shifted emission and absorption bands are well-known for molecular aggregates, where the coherent coupling in J-/H-aggregates can lead to super/subradiant emission. (75) Hence, we interpret the emergence of this additional emission band next to the excitonic PL band as emission that originates from coupled NC that is induced by the NC assembly into ordered SLs. The energy splitting between these bands may be viewed as a signature of the coupling strength. In Figure 17a, we show the emission spectra of two b-ABO3 SLs with 8.6 nm CsPbBr3 nanocubes and iron oxide NCs of different sizes. As the A-sphere (Fe3O4) size increases from 14.5 to 19.5 nm, so does also the lattice parameter and hence the B–O sites distance (from 10.2 to 11.8 nm), as seen experimentally by TEM and GISAXS. The PL peak energy splitting between uncoupled NCs and the coupled NCs decreases from 54 ± 7 meV to 37 ± 5 meV (Figure 17a). In b-ABO3-type SLs, NCs are in very close proximity (the distance between inorganic cores of perovskite NCs is below 1.4 nm), potentially allowing a wave function tunneling. Contrary to the long-range dipole–dipole coupling, which exhibits a characteristic 1/D6 scaling of the coupling strength as a function of the distance D between the dipoles, Dexter-like wave function tunneling is expected to exhibit exponential behavior. The exact determination of the underlying physical mechanism responsible for the NC coupling remains to be further explored; in particular, whether B–O or O–O sites couple by the short-range wave function overlap or whether there exists longer-range B–B (a unit cell apart) dipolar coupling or similar.

Figure 17

Figure 17. PL properties of ABO3-type binary SLs at 6 K. (a) PL spectra of binary ABO3-type SLs assembled by employing 8.6 nm CsPbBr3 and 19.5 nm (top) or 14.5 nm (bottom) Fe3O4 NCs. The PL spectra (black solid lines) are fitted to a doubled Lorentzian function (red and blue lines are the individual functions, while the gray lines are the cumulative fits to the experimental data). (b) Measured coupled vs uncoupled splitting energy for several samples with different distances between O-site and B-site NCs. Error bars denote the standard deviation obtained by measuring several PL spectra on different locations on the same sample.

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In molecular aggregates, the coupling between the constituent molecules and, therefore, the aggregate emission band can exhibit peculiar temperature trends. (75) In order to shed light on the role of such phonon-related processes within the NC aggregates, temperature-dependent measurements were carried out on AlB2 SLs formed by 5.3 nm CsPbBr3 NCs and 12.5 nm iron oxide NCs. We chose this SL structure given the large energetic splitting (ca. 140 meV) observed for this SL type. Although the geometry of the perovskite NC sublattice and crystallographic alignment of NCs is vastly different than in b-ABO3 SLs, thus precluding a trustful comparison, the enhanced red-shift could be assigned to the shorter NC–NC distance (ca. 9.5 nm) and higher quantum confinement obtained with 5.3 nm CsPbBr3 NCs. Figure 18a shows typical PL spectra at low (6 K) and elevated (100 K) temperatures, whereas complete temperature evolution is shown in Figure 18b. While the emission band of the uncoupled NCs (near 2.50 eV) shifts only slightly to blue, the emission from the coupled NCs shifts more, reducing the energetic splitting and decreasing in relative intensity while broadening. Spectral substructure of the coupled PL band is occasionally seen (inset of Figure 18a), which we attribute to several distinct aggregate domains being present within the excitation beam spot of ca. 2 μm2. We note that while a large fraction of studied SLs display the red-shifted emission from coupled NCs, its appearance still varies from sample to sample, probably due to the very short-range nature of the coupling, being it either wave function tunneling or partial necking of the NCs.

Figure 18

Figure 18. Impact of the temperature on the PL band from coupled NCs in AlB2-type binary SLs (5.3 nm CsPbBr3 NCs + 12.5 nm Fe3O4 NCs). (a) Normalized PL spectra for the AlB2-type SLs at 6 and 100 K. The inset reports a zoom-in PL spectrum for a nominally similar sample where much narrower emission peaks are resolved (full width at half-maximum of about 3 meV, dashed line). (b) Two-dimensional colored plot of normalized PL spectra obtained at different temperatures. (c) The relative amplitude of the two emission bands as a function of temperature (black open circles). The red solid line is the best fit to an Arrhenius plot returning activation energy of 14 meV, very close to the LO-phonon energy of CsPbBr3 crystal (17 meV). (d) Extracted splitting energy is plotted vs the squared root of the red-shifted peak area, exhibiting a linear dependence (solid red line).

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The ratio between the coupled (aggregate) and the uncoupled (nonaggregate) NC emission is plotted in Figure 18c, along with an Arrhenius fit, returning activation energy of about 14 meV, close to the LO-phonon energy in CsPbBr3 NCs (17 meV). (76,77) This suggests that a phonon-driven mechanism similar to that in molecular aggregates reduces the effective number of coupled emitters N with temperature rise. This notion is supported by rather linear correlation obtained when plotting the splitting ΔE between the coupled and the uncoupled emission bands vs the square root of the peak area of the coupled emission (using the temperature-dependent data), which represents the number of coupled emitters (ΔE ∝ √N, Figure 18d). This dependency and the emission of coupled NCs being far from the expected bulk emission (ca. 2.3 eV, 535–540 nm) as well as a very strong quenching of the red aggregate band already at intermediate temperatures would hardly be reconcilable with an alternative assumption that the red-shifted emission peak could originate from the bulk material forming during the aggregation process. (78) The latter would imply an order of magnitude reduction of bulk emission quantum yield just within this temperature range.
Further evidence for red-shifted PL band originating from coupled NCs is found in the absorption spectra, presented here for b-ABO3-type SLs (8.8 nm CsPbBr3 + NaGdF4 NCs, Figure 19). These SLs exhibit two emission bands with a relative energetic splitting (ΔE) scaling with the NC-to-NC distances: on average, 45 and 37 meV for 15.1 and 18.2 nm NaGdF4 NCs, respectively (Figure 19, top and middle panels). The red-shifted band is also resolved in absorption, similar to our earlier studies on single-component SLs. (53) Similar to the PL behavior, the relative energetic splitting scales with the lattice parameter of the SL. The temperature behavior is analogous too; an additional absorption band vanishes when reaching 200 K (Figure 19), being strong evidence that rules out the hypothesis attributing the red-shifted PL band to bulk inclusions. (78) In particular, while a drop of the PL intensity from the bulk inclusions upon heating could be rationalized by the rapidly decaying PL quantum yield, the absorbance must persist.

Figure 19

Figure 19. PL and absorbance spectra of binary ABO3-type SLs comprising 8.8 nm CsPbBr3 cubes and 18.2 nm (top panel) or 15.1 nm (middle panel) NaGdF4 spherical NCs, measured at 10 K (top and middle panel) and 200 K (bottom panel).

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Conclusions

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In summary, we have presented a full survey of multicomponent SLs comprising sharp, sub-10 nm cubic perovskite NCs, obtained thus far in our experiments by combining them with spherical, truncated cubic, and disk-shaped NCs. Three SL structure types are of the kind commonly reported for binary mixtures of spherical NCs (NaCl, AlB2, and CuAu types). Three other binary structures (perovskite ABO3, AB2, ABO6) are related to the cubic shape of perovskite NC building blocks. AB2 can be viewed as derived from AlB2 by slipping each fourth (100)SL in an [011]SL direction. ABO6 can be conceived as the ABO3 lattice, wherein each O-site is occupied by two 5.3 nm CsPbBr3 cubes. When an anisotropic NC counter building block is utilized, namely, thick NaGdF4 nanodisks (18.5 nm thick, 31.5 nm in diameter), a CaC2-like lattice forms, wherein the 8.6 nm cubes occupy the “C2-site”, and the anisotropy of disks reduces tetragonal symmetry of the unit cell into orthogonal. In all studied SLs, cubic NCs are orientationally locked. We also report a substrate-less growth of thin-film SLs by drying colloids atop of an immiscible liquid (glyceryl triacetate) or of SL supraparticles with the aid of emulsion. Low-temperature PL and absorption spectra attest emergence of collective states in these highly dense aggregates of highly luminescent NCs.

Experimental Section

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Synthesis of Cesium Oleate Stock Solution

Cs2CO3 (0.2 g, Sigma-Aldrich, 99.9%), oleic acid (0.6 mL, OA, Sigma-Aldrich, 90%, vacuum-dried at 100 °C), and 1-octadecene (7.5 mL, ODE, Sigma-Aldrich, 90%, distilled) were loaded into 25 mL flask, dried under vacuum for 20 min at 100 °C, and then heated under N2 to 120 °C until all the Cs2CO3 reacted with OA.

Synthesis of CsPbBr3 NCs

The 8.6 nm NCs were synthesized following the method reported in ref (62). In a 25 mL three-neck flask, PbBr2 (55 mg, ABCR, 98%) was degassed three times, suspended in 5 mL of ODE, and degassed three times again at room temperature. The suspension was quickly heated to 180 °C, when the temperature reached 120 °C, 0.5 mL of OA and oleylamine (0.5 mL, OLA, Strem, 97%, distilled) were injected. At 180 °C, preheated to about 100 °C cesium oleate solution in ODE (0.6 mL) was injected. The reaction mixture was cooled immediately to room temperature with an ice bath. The crude solution was centrifuged at 12,100 rpm (equivalent to 20,130 relative centrifugal force) for 5 min, the supernatant was discarded, and the precipitate was dispersed in hexane (0.3 mL, Sigma-Aldrich, anhydrous, 95%). The solution was centrifuged again at 10,000 rpm for 3 min, and the precipitate was discarded. Then, OLA/OA ligands were exchanged by DDAB treatment. 0.3 mL hexane, toluene (0.6 mL, Sigma-Aldrich, anhydrous, 99.8%), and DDAB (0.14 mL, 0.05 M in toluene, Sigma-Aldrich, 98%) were added to the supernatant and stirred for 1 h, followed by destabilization with ethyl acetate (1.8 mL, Sigma-Aldrich, 99.9%), centrifuging at 12,100 rpm for 3 min and redispersing in 0.6 mL of toluene. Synthesis of 5.3 nm CsPbBr3 NCs was adopted from ref (61) followed by DDAB treatment. The concentration of CsPbBr3 NCs was calculated from the optical absorption at 335 nm using the reported molar extinction coefficient. (79) The concentration of other NCs was determined gravimetrically, accounting for capping ligands with the grafting densities stated in Supplementary Note 2.

Synthesis of NaGdF4 NCs by Thermal Decomposition of Gadolinium Trifluoroacetate (31)

Gadolinium trifluoroacetate (147 mg, 0.267 mmol), NaF (16.1–22.4 mg, 0.383–0.533 mmol, lower loading resulted in larger NCs size, Merk, 99.99%), 4 mL of OA, and 4 mL of ODE were degassed in a three-neck flask at 125 °C for 70 min. Then the solution was heated to 312 °C at 15 °C/min under nitrogen and kept at this temperature for 75 min. The reaction mixture was cooled to room temperature, and 36 mL of ethanol (Merck, 99.8%) was added to destabilize the colloidal solution. The NCs were precipitated by centrifugation at 4000 rpm for 3 min and washed three additional times with hexane (along with 25 μL OA) and ethanol (1 to 1.5 by volume). After purification, NCs were stored in 2 mL of hexane. Gadolinium trifluoroacetate was synthesized by reaction of Gd2O3 (2.159 g, 6 mmol, Sigma-Aldrich, 99.9%) with trifluoroacetic acid (7.4 mL, 95 mmol, Sigma-Aldrich, 99%) and 12.4 mL of water under reflux (93 °C) for 1 h. The white product was isolated by evaporation of the unreacted acid and water under vacuum at 60 °C and dried overnight under vacuum.
For the synthesis of NaGdF4 disks, gadolinium trifluoroacetate (221 mg, 0.4 mmol), NaF (29.5 mg, 0.7 mmol), 6 mL of OA, and 6 mL of ODE were degassed in a three-neck flask at 125 °C for 90 min. Then the solution was heated to 312 °C at 15 °C/min under nitrogen and kept at this temperature for 83 min. The reaction mixture was cooled to room temperature, then 2 mL of hexane and 36 mL of ethanol were added to destabilize the colloidal solution. The NCs were precipitated by centrifugation at 5000 rpm for 2 min and washed additionally twice with hexane (along with 40 μL of OA) and ethanol (1:2.5 by volume). After purification, NCs were stored in 2 mL of toluene.

Synthesis of Truncated Cubic PbS NCs (80)

For a synthesis of 10.7 nm PbS NCs, PbO (278.8 mg, 1.25 mmol, Aldrich, 99%), OA (3.125 mL, 9.88 mmol), and 6.25 mL of ODE were degassed in a three-neck flask for 30 min at room temperature and 30 min at 100 °C. Then the solution was flushed with nitrogen and heated to 200 °C. At this temperature, sulfur (40 mg, 1.25 mmol, Fluka, 99.5%) dissolved in OLA (1.25 mL 3.8 mmol) was swiftly injected. The reaction mixture was cooled to room temperature with a water bath after 5 min of stirring. The NCs were washed four times with hexane (along with 25 μL OA) and ethanol (3:1 by volume) and stored in hexane. For the synthesis of 11.7 nm PbS NCs, the mixture of 2.2 mL of OA with 7.2 mL of ODE was used as a solvent, and the reaction temperature was increased to 205 °C.

Synthesis of Fe3O4 NCs by Thermal Decomposition of Iron Oleate (63)

For the synthesis of iron oleate complex, FeCl3 (1.658 g, 10 mmol, Alfa-Aesar, 98%) and sodium oleate (9.125 g, 30 mmol, TCI, 97%) were dissolved in a mixture of 35 mL of hexane, 20 mL of ethanol, and 15 mL of distilled water. After stirring under nitrogen at 65 °C for 5 h, the upper organic layer was separated and washed five times with warm water, followed by centrifugation and isolation in a separatory funnel. The waxy solid product was isolated using a rotary evaporator and dissolved in ODE to form 0.4 mol/kg solution. In a typical synthesis of 15.6 nm Fe3O4 NCs, iron oleate complex in ODE (5 mL), OA (0.8 mL, 2.53 mmol), and 5 mL of ODE were loaded into a three-neck flask and vacuum dried at 110 °C for 90 min. The reaction mixture was then heated under nitrogen from 200 to 312 °C with a constant heating rate of 2 °C/min and maintained at this temperature for 30 min after the initiation took place. The solution was cooled to room temperature and washed with 3 mL of hexane and 12 mL of acetone, followed by centrifugation at 8000 rpm for 3 min. The precipitate was dissolved in 3 mL of hexane with 25 μL of OA. After two additional rounds of purification with hexane and acetone (2:1 by volume), the NCs were dispersed in 3 mL hexane. The size of NCs was controlled by varying the concentration of OA (higher for larger NCs) and reaction temperature (higher for larger NCs).

Synthesis of 12.5 nm LaF3 Nanodisks by Thermal Decomposition of Lanthanum Trifluoroacetate (37)

Lanthanum trifluoroacetate (192 mg), LiF (31.2 mg, Sigma-Aldrich, 99.99%), 6 mL of OA, and 6 mL of ODE were degassed in a 25 mL three-neck flask at 125 °C for 2 h. Then the solution was heated to 300 °C at 15 °C/min under nitrogen and kept at this temperature for 70 min. The reaction mixture was cooled to room temperature, and 3 mL of hexane along with ethanol (30 mL) was added to destabilize the colloidal solution. The NCs were precipitated by centrifugation at 4000 rpm for 2 min and washed two additional times with hexane (along with 10–30 μL of OA) and ethanol (1:1 by volume). After purification, NCs were dispersed in 3 mL of hexane, and residual LiF, which is not soluble in nonpolar solvents, was separated by centrifugation at 4000 rpm for 2 min. Lanthanum trifluoroacetate was synthesized by reaction of La2O3 (3.24 g, Sigma-Aldrich, 99.999%) with trifluoroacetic acid (16 mL) and 16 mL of water under reflux (93 °C) for 1 h. The white product was isolated by evaporation of the unreacted acid and water under vacuum at 60 °C and dried overnight under vacuum.

Preparation of Multicomponent SLs

Self-assembly of NCs was carried out using a drying-mediated method on carbon-coated TEM grids (carbon type B, Ted Pella, Formvar protective layer was removed by immersing the grid in toluene for 10 s), HF-treated silicon, and silicon nitride TEM windows (Agar Scientific, Norcada). A mixture of NCs in anhydrous toluene had an overall particle concentration of 0.5–2 μM and NC number ratios in the range of 0.5–20. 28–35 μL of NC mixture was transferred into a tilted 2 mL glass vial with a substrate inside. The solvent was evaporated under 0.5 atm pressure at room temperature. For example, binary ABO3-, AlB2-, and NaCl-type SLs were obtained with high yields on TEM grids upon slow drying of the solutions prepared by mixing 15.2 nm NaGdF4 NCs (29 mg/mL, 1.8, 2.0, and 2.4 μL, respectively) and 5.3 nm CsPbBr3 NCs (7.5 μM; 4.7, 2.6, and 1.7 μL, respectively) with anhydrous toluene (25 μL); binary ABO3-type SL, 11.7 nm PbS NCs (1.8 μM, 3 μL), 8.6 nm CsPbBr3 NCs (5.0 μM, 7 μL) and 25 μL of toluene; binary NaCl-type SL, 11.7 nm PbS NCs (1.8 μM, 2.8 μL), 8.6 nm CsPbBr3 NCs (3.9 μM, 3 μL) and 25 μL of toluene.
For the assembly of single-component CsPbBr3 NCs film at the liquid–air interface, a 1 × 1 cm2 Teflon well was filled with 0.5 mL of glyceryl triacetate (Sigma-Aldrich, 99%), CsPbBr3 NCs in octane (0.4 μM, 20 μL) were dropped onto the surface, and then the well was covered by glass slide and octane slowly evaporated. After drying was completed, the film was transferred to a carbon-coated TEM grid, and the substrate was further dried under vacuum to get rid of the residual subphase. For the assembly of NaCl-type film, the mixture of 8.6 nm CsPbBr3 NCs (4.3 μM, 2.5 μL, in toluene), 19.5 nm Fe3O4 NCs (39 mg/mL, 2.5 μL, in toluene), and 10 μL of decane was dropped onto the surface of glyceryl triacetate in Teflon well following the aforementioned procedure. For the assembly of the AlB2-type film, the mixture of 8.6 nm CsPbBr3 NCs (4.3 μM, 9 μL, in toluene), 19.5 nm Fe3O4 NCs (39 mg/mL, 6 μL, in toluene), and 100 μL of decane was dropped onto the surface of glyceryl triacetate (1.5 mL) in Petri dish (3 cm in diameter), covered by glass slide following the aforementioned procedure.
For the typical microemulsion-templated self-assembly, solution 1 (CsPbBr3 and NaGdF4 NCs in toluene with the total NCs concentration about 5 mg/mL) was added into solution 2 (fluorosurfactant 008-FS in fluorinated solvent FC-40). Then, the resulting suspension was mixed with a vortex mixer or a homogenizer. Emulsified solution was slowly stirred for 24–48 h until the toluene was evaporated. For the assembly of a b-ABO3-type micelle, the mixture of 8.6 nm CsPbBr3 NCs (1.7 μM, 25 μL, in toluene), 18.6 nm NaGdF4 NCs (9 mg/mL, 82 μL, in toluene), and 60 μL of toluene was added to the solution of 5 wt % 008-FS in FC-40 (50 μL, RAN Biotechnologies) and FC-40 (283 μL, abcr) following the aforementioned procedure. For the assembly of an orthorhombic CaC2-like micelle, the mixture of 8.6 nm CsPbBr3 NCs (1.3 μM, 45 μL, in toluene), 31.5 nm NaGdF4 NCs (2 mg/mL, 90 μL, in toluene), and 32 μL of toluene was added to the solution of 5 wt % 008-FS in FC-40 (50 μL) and FC-40 (283 μL) following the aforementioned procedure.

Electron Microscopy Characterization

TEM and HAADF-STEM images as well as ED and small-angle ED patterns were collected with the use of JEOL JEM2200FS microscope operating at 200 kV accelerating voltage. EDX-STEM maps and HAADF-STEM images at different tilt angles were recorded using an FEI Titan Themis microscope operated at 300 kV equipped with a SuperEDX detector, with the aid of a motorized dual-axis tomography holder. Captured TEM and electron diffraction images were compared with the ones simulated in Crystal Maker 10.4.5 and Single Crystal 3.1.5 software, purchased from CrystalMaker Software Ltd. Electron tomography was carried out in HAADF-STEM mode at 300 kV using a small beam semiconvergence angle of 2.5 mrad, to increase the depth of field. Images were recorded over a tilt angle range ± (57–72)° and interval 2–3°. Reconstruction was done using IMOD with a Back Projection algorithm and SIRT-like radial filter. (81) The tomograms were recorded on SLs self-assembled on carbon-coated TEM grids as continuous films or via a microemulsion technique. SEM images were obtained on a FEI Helios 660 operated at 3–7 kV using immersion mode.

Atomic Force Microscopy

ScanAsyst-AiIR probes were used to analyze the topography of the SLs on the Bruker Icon 3 atomic force microscope.

GISAXS Characterization

GISAXS measurements were performed at the Austrian SAXS beamline of the electron storage ring ELETTRA using a photon energy of 8 keV. (82) The beamline setup was adjusted to a sample to detector distance of 1961.43 mm to result in an accessible horizontal scattering vector q-range of −1.2 nm–1 < qH < 1.8 nm–1 and vertical scattering vector q-range of −0.1 nm–1 < qV < 2.9 nm–1. The X-ray beam was collimated to a spot size at the sample of approximately 200 μm × 200 μm. The images were recorded using the Pilatus 1 M detector (Dectris, Switzerland) with an exposure time of 10 s per image. Reference patterns to calibrate the q-scale were collected of silver-behenate (d-spacings of 5.838 nm). Samples were mounted on a 2-axis goniometer stage with 0.001° angular precision, allowing us to ensure an incidence angle of 0.04° for the measurements (determined by alignment of the specular reflection on the detector). The presented data were corrected for fluctuations of the primary intensity. Data treatment was done using the NIKA2D (83) (geometry correction and calibration) as well as GIXSGUI (84) (lattice indexing) software packages.

Optical Spectroscopy

For the PL measurements, the sample was mounted on an XYZ nanopositioning stage inside an evacuated liquid-helium coldfinger cryostat and cooled to 6 K. Nanocrystals were excited with a fiber-coupled excitation laser at a photon energy of 3.06 eV with pulses of 50 ps duration. A long working-distance, 100×, microscope objective with a numerical aperture of 0.7 was used for both excitation and detection, leading to a Gaussian excitation spot with a 1/e2 diameter of 1.4 μm. The emission was then dispersed in a 750 mm monochromator by a 3000 lines per mm grating and detected with a back-illuminated, cooled EMCCD camera.
For absorption and PL experiments reported in Figure 19, a custom-made setup, enabling both experiments to probe the same sample area, was used. The samples were placed on the coldfinger of a Janis CCS-150 closed-cycle optical refrigerator, allowing temperature variation within the 10–300 K range. Steady-state PL was excited by a 405 nm diode laser, focused onto a ∼2 μm diameter spot, via a Mitutoyo long working distance objective with 50× magnification and 0.55 numerical aperture. The emission was detected via the same objective, using a long-pass filter to block the excitation laser, while spectrally analyzed by a 0.75 m Acton750i Princeton spectrometer equipped with a 1024 × 256 pixels PIXIS charge-coupled device (CCD) camera. For absorption measurements, a tungsten-halogen white light source was coupled into a 600 μm core multimode fiber, and the output beam was focused onto the sample via the same microscope objective described above. The transmitted beam was coaxially collected and analyzed via the same combination of spectrometer and CCD described above.

Optical Properties of CsPbBr3 NCs in Toluene

Optical absorption spectra were measured with Jasco V770 spectrometer in transmission mode. PL spectra were measured in a 90° configuration using Horiba Fluoromax-4P+ equipped with a photomultiplier tube and a monochromatized 150 W xenon lamp as an excitation source.

Supporting Information

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including three Supplementary Video files. The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsnano.1c10702.

  • Video S1: Tomographic reconstruction of binary AlB2-type SL comprising 5.3 nm CsPbBr3 nanocubes and 15.2 nm NaGdF4 spherical NCs (AVI)

  • Video S2: Tomographic reconstruction of binary CaC2-type SL comprising 8.6 nm CsPbBr3 nanocubes and 31.5 nm NaGdF4 thick nanodisks (AVI)

  • GISAXS characterization of AlB2-type SL; packing analysis of AlB2-, AB2- and b-ABO6-type SLs; additional TEM characterization of NC building blocks and binary NC SLs (PDF)

  • Video S3: Tomographic reconstruction of binary ABO3-type supraparticle comprising 8.6 nm CsPbBr3 nanocubes and 18.6 nm NaGdF4 spherical NCs (AVI)

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Author Information

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  • Corresponding Authors
    • Maksym V. Kovalenko - Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland;  Laboratory for Thin Films and Photovoltaics and , Empa−Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland;  Orcidhttps://orcid.org/0000-0002-6396-8938;  Email: [email protected]
    • Maryna I. Bodnarchuk - Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland;  Laboratory for Thin Films and Photovoltaics and , Empa−Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland;  Orcidhttps://orcid.org/0000-0001-6597-3266;  Email: [email protected]
  • Authors
    • Ihor Cherniukh - Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland;  Laboratory for Thin Films and Photovoltaics and , Empa−Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland;  Orcidhttps://orcid.org/0000-0001-7155-5095
    • Taras V. Sekh - Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland;  Laboratory for Thin Films and Photovoltaics and , Empa−Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
    • Gabriele Rainò - Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland;  Laboratory for Thin Films and Photovoltaics and , Empa−Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland;  Orcidhttps://orcid.org/0000-0002-2395-4937
    • Olivia J. Ashton - Electron Microscopy Center and , Empa−Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland;  Orcidhttps://orcid.org/0000-0002-0886-2110
    • Max Burian - Swiss Light Source, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland;  Orcidhttps://orcid.org/0000-0001-6728-6347
    • Alex Travesset - Department of Physics and Astronomy and Ames Laboratory, Iowa State University, Ames, Iowa 50011, United States;  Orcidhttps://orcid.org/0000-0001-7030-9570
    • Modestos Athanasiou - Experimental Condensed Matter Physics Laboratory, Department of Physics, University of Cyprus, 1678 Nicosia, Cyprus;  Orcidhttps://orcid.org/0000-0003-1684-9482
    • Andreas Manoli - Experimental Condensed Matter Physics Laboratory, Department of Physics, University of Cyprus, 1678 Nicosia, Cyprus
    • Rohit Abraham John - Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland;  Laboratory for Thin Films and Photovoltaics and , Empa−Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland;  Orcidhttps://orcid.org/0000-0002-1709-0386
    • Mariia Svyrydenko - Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland;  Laboratory for Thin Films and Photovoltaics and , Empa−Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
    • Viktoriia Morad - Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland;  Laboratory for Thin Films and Photovoltaics and , Empa−Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
    • Yevhen Shynkarenko - Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland;  Laboratory for Thin Films and Photovoltaics and , Empa−Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
    • Federico Montanarella - Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland;  Laboratory for Thin Films and Photovoltaics and , Empa−Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland;  Orcidhttps://orcid.org/0000-0002-9057-7414
    • Denys Naumenko - Institute of Inorganic Chemistry, Graz University of Technology, 8010 Graz, Austria
    • Heinz Amenitsch - Institute of Inorganic Chemistry, Graz University of Technology, 8010 Graz, Austria
    • Grigorios Itskos - Experimental Condensed Matter Physics Laboratory, Department of Physics, University of Cyprus, 1678 Nicosia, Cyprus;  Orcidhttps://orcid.org/0000-0003-3971-3801
    • Rainer F. Mahrt - IBM Research Europe−Zurich, CH-8803 Rüschlikon, Switzerland;  Orcidhttps://orcid.org/0000-0002-9772-1490
    • Thilo Stöferle - IBM Research Europe−Zurich, CH-8803 Rüschlikon, Switzerland;  Orcidhttps://orcid.org/0000-0003-0612-7195
    • Rolf Erni - Electron Microscopy Center and , Empa−Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland;  Orcidhttps://orcid.org/0000-0003-2391-5943
  • Notes
    The authors declare no competing financial interest.

Acknowledgments

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This work was supported by the Swiss National Science Foundation (grant number 200021_192308, project Q-Light) and, in part, by the European Union through Horizon 2020 Research and Innovation Programme (ERC CoG Grant, grant agreement number 819740, project SCALE-HALO) and by the Air Force Office of Scientific Research under award number FA8655-21-1-7013. The authors acknowledge support by the Research and Innovation Foundation of Cyprus, under the “New Strategic Infrastructure Units-Young Scientists” Program, grant agreement number “INFRASTRUCTURES/1216/0004”, Acronym “NANOSONICS”. M.A. acknowledges financial support by the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement number 831690. We acknowledge the funding received from EU-H2020 under grant agreement number 654360 supporting the Transnational Access Activity within the framework NFFA-Europe to the TUG’s ELETTRA SAXS beamline of CERIC–ERIC. A.T. acknowledges the funding received from the National Science Foundation (USA) DMR-CMMT 1606336. F.M. acknowledges support from ETH Zürich via the ETH Postdoctoral Fellowship (FEL-15 18-2) and from the Marie Skłodowska-Curie Actions COFUND Program. We thank M. Rossell for the high-resolution HAADF-STEM image used in Figure 1. The authors are grateful for the use of facilities at the Empa Electron Microscopy Center.

References

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This article references 84 other publications.

  1. 1
    Boles, M. A.; Engel, M.; Talapin, D. V. Self-Assembly of Colloidal Nanocrystals: From Intricate Structures to Functional Materials. Chem. Rev. 2016, 116, 11220– 11289,  DOI: 10.1021/acs.chemrev.6b00196
    Google Scholar
    1
    Self-Assembly of Colloidal Nanocrystals: From Intricate Structures to Functional Materials
    Boles, Michael A.; Engel, Michael; Talapin, Dmitri V.
    Chemical Reviews (Washington, DC, United States) (2016), 116 (18), 11220-11289CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
    A review. Chem. methods developed over the past two decades enable prepn. of colloidal nanocrystals with uniform size and shape. These Brownian objects readily order into superlattices. Recently, the range of accessible inorg. cores and tunable surface chemistries dramatically increased, expanding the set of nanocrystal arrangements exptl. attainable. In this review, we discuss efforts to create next-generation materials via bottom-up organization of nanocrystals with preprogrammed functionality and self-assembly instructions. This process is often driven by both interparticle interactions and the influence of the assembly environment. The introduction provides the reader with a practical overview of nanocrystal synthesis, self-assembly, and superlattice characterization. We then summarize the theory of nanocrystal interactions and examine fundamental principles governing nanocrystal self-assembly from hard and soft particle perspectives borrowed from the comparatively established fields of micrometer colloids and block copolymer assembly. We outline the extensive catalog of superlattices prepd. to date using hydrocarbon-capped nanocrystals with spherical, polyhedral, rod, plate, and branched inorg. core shapes, as well as those obtained by mixing combinations thereof. We also provide an overview of structural defects in nanocrystal superlattices. We then explore the unique possibilities offered by leveraging nontraditional surface chemistries and assembly environments to control superlattice structure and produce nonbulk assemblies. We end with a discussion of the unique optical, magnetic, electronic, and catalytic properties of ordered nanocrystal superlattices, and the coming advances required to make use of this new class of solids.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhtlyisbnO&md5=274e85cfde9882c4a5f718ca0434e1dd
  2. 2
    Tan, R.; Zhu, H.; Cao, C.; Chen, O. Multi-Component Superstructures Self-Assembled from Nanocrystal Building Blocks. Nanoscale 2016, 8, 9944– 9961,  DOI: 10.1039/C6NR01662F
    Google Scholar
    2
    Multi-component superstructures self-assembled from nanocrystal building blocks
    Tan, Rui; Zhu, Hua; Cao, Can; Chen, Ou
    Nanoscale (2016), 8 (19), 9944-9961CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)
    More than three decades of intensive study to make high-quality nanocrystals have created a unique toolbox for building multi-component superstructures, which have been recognized as a new generation of metamaterials important to both fundamental sciences and applied technologies. This minireview summarizes recent advances in this exciting field. We will focus our discussion on the synthetic strategies and superstructures of this multi-component metamaterial, and highlight their novel properties and potential applications. Addnl., some perspectives on possible developments in this field are offered at the end of this review. We hope that this minireview will both inform and stimulate research interests for the design and fabrication of these nanocrystal-based multi-component metamaterials for diverse applications in the future.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xms1Wgtro%253D&md5=10379c2b1ee8d30ef92dd6aaf1912454
  3. 3
    Urban, J. J.; Talapin, D. V.; Shevchenko, E. V.; Kagan, C. R.; Murray, C. B. Synergism in Binary Nanocrystal Superlattices Leads to Enhanced P-Type Conductivity in Self-Assembled PbTe/Ag2Te Thin Films. Nat. Mater. 2007, 6, 115– 121,  DOI: 10.1038/nmat1826
    Google Scholar
    3
    Synergism in binary nanocrystal superlattices leads to enhanced p-type conductivity in self-assembled PbTe/Ag2Te thin films
    Urban, Jeffrey J.; Talapin, Dmitri V.; Shevchenko, Elena V.; Kagan, Cherie R.; Murray, Christopher B.
    Nature Materials (2007), 6 (2), 115-121CODEN: NMAACR; ISSN:1476-1122. (Nature Publishing Group)
    The ordered cocrystn. of nanoparticles into binary superlattices enables close contact of nanocrystals with distinct phys. properties, providing a route to 'metamaterials' design. Here the authors present the 1st electronic measurements of multicomponent nanocrystal solids composed of PbTe and Ag2Te, demonstrating synergistic effects leading to enhanced p-type cond. First, syntheses of size-tuneable PbTe and Ag2Te nanocrystals are presented, along with deposition as thin-film nanocrystal solids, whose electronic transport properties were characterized. Next, assembly of PbTe and Ag2Te nanocrystals into AB binary nanocrystal superlattices is demonstrated. Also, binary composites of varying PbTe-Ag2Te stoichiometry (1:1 and 5:1) were prepd. and electronically characterized. These composites show strongly enhanced (conductance ∼100-fold increased in 1:1 composites over the sum of individual conductances of single-component PbTe and Ag2Te films) p-type electronic cond. This observation, consistent with the role of Ag2Te as a p-type dopant in bulk PbTe, demonstrates that nanocrystals can behave as dopants in nanostructured assemblies.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXhtFyhsrw%253D&md5=88c92965e961ac22b0faa11aba67c8ce
  4. 4
    Chen, J.; Ye, X.; Oh, S. J.; Kikkawa, J. M.; Kagan, C. R.; Murray, C. B. Bistable Magnetoresistance Switching in Exchange-Coupled CoFe2O4-Fe3O4 Binary Nanocrystal Superlattices by Self-Assembly and Thermal Annealing. ACS Nano 2013, 7, 1478– 1486,  DOI: 10.1021/nn3052617
    Google Scholar
    4
    Bistable Magnetoresistance Switching in Exchange-Coupled CoFe2O4-Fe3O4 Binary Nanocrystal Superlattices by Self-Assembly and Thermal Annealing
    Chen, Jun; Ye, Xingchen; Oh, Soong Ju; Kikkawa, James M.; Kagan, Cherie R.; Murray, Christopher B.
    ACS Nano (2013), 7 (2), 1478-1486CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
    Self-assembly of multicomponent nanocrystal superlattices provides a modular approach to the design of metamaterials by choosing constituent nanocrystal building blocks with desired phys. properties and engineering the interparticle coupling. The authors report the self-assembly of binary nanocrystal superlattices composed of magnetically hard CoFe2O4 nanocrystals and magnetically soft Fe3O4 nanocrystals. Both NaZn13- and MgZn2-type CoFe2O4-Fe3O4 binary nanocrystal superlattices were formed by the liq.-air interfacial assembly approach. Exchange coupling is achieved in both types of binary superlattices after thermal annealing under vacuum at 400°. The exchange-coupled CoFe2O4-Fe3O4 binary nanocrystal superlattices show single-phase magnetization switching behavior and magnetoresistance switching behavior <200 K. The NaZn13-type CoFe2O4-Fe3O4 binary nanocrystal superlattices annealed at 500° even exhibit bistable magnetoresistance switching behavior at room temp. constituting a simple nonvolatile memory function.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXjslKl&md5=fb772c9528b9eccd7ae409e005bb48fc
  5. 5
    Ye, X.; Chen, J.; Diroll, B. T.; Murray, C. B. Tunable Plasmonic Coupling in Self-Assembled Binary Nanocrystal Superlattices Studied by Correlated Optical Microspectrophotometry and Electron Microscopy. Nano Lett. 2013, 13, 1291– 1297,  DOI: 10.1021/nl400052w
    Google Scholar
    5
    Tunable Plasmonic Coupling in Self-Assembled Binary Nanocrystal Superlattices Studied by Correlated Optical Microspectrophotometry and Electron Microscopy
    Ye, Xingchen; Chen, Jun; Diroll, Benjamin T.; Murray, Christopher B.
    Nano Letters (2013), 13 (3), 1291-1297CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
    The authors study the plasmonic properties of self-assembled binary nanocrystal superlattices (BNSLs) using correlated optical microspectrophotometry and electron microscopy performed on individual BNSL domains. The strength of near-field couplings between adjacent plasmonic nanocrystals (NCs) can be systematically engineered by varying the NC size, compn., and the lattice symmetry of BNSLs, leading to broadband spectral tunability of the collective plasmonic response of BNSLs across the entire visible spectrum. Self-assembled multicomponent NC superlattices represent a versatile platform for the rational design of macroscopic 3-dimensional plasmonic metamaterials with emergent optical characteristics.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXivVyiu7s%253D&md5=78668edb12cbb764692492d9eff59c08
  6. 6
    Talapin, D. V.; Shevchenko, E. V.; Kornowski, A.; Gaponik, N.; Haase, M.; Rogach, A. L.; Weller, H. A New Approach to Crystallization of CdSe Nanoparticles into Ordered Three-Dimensional Superlattices. Adv. Mater. 2001, 13, 1868– 1871,  DOI: 10.1002/1521-4095(200112)13:24<1868::AID-ADMA1868>3.0.CO;2-0
    Google Scholar
    6
    A new approach to crystallization of CdSe nanoparticles into ordered three-dimensional superlattices
    Talapin, Dmitri V.; Shevchenko, Elena V.; Kornowski, Andreas; Gaponik, Nikolai; Haase, Markus; Rogach, Andrey L.; Weller, Horst
    Advanced Materials (Weinheim, Germany) (2001), 13 (24), 1868-1871CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH)
    Two types of colloidal crystals consisting of CdSe nanocrystals were prepd. by the method of controlled oversatn. in solns. At 1st, the CdSe nanocrystals were prepd. from either trioctylphosphine oxide/trioctylphosphine (TOPO-TOP) or hexadecylamine (HDA)-TOPO-TOP mixts. starting from TOPSe and (Me2)Cd. Their growth was monitored by UV-vis absorption spectroscopy and the nanocrystals were redissolved in toluene. Then, a non-solvent (MeOH) was slowly introduced into the concd. soln. of the monodisperse CdSe nanocrystals in toluene. The diffusion of MeOH was carried out directly or through a buffer layer of a 3rd component (propan-2-ol). In the 1st case, irregular shaped crystals were obtained, while the slower diffusion through the buffer layer resulted in perfectly faceted hexagonal platelets with a size of 100 μm. The samples were characterized by XRD, high-resoln. TEM, optical microscopy, and absorption and photoluminescence spectroscopy. CdSe quantum dots were crystd. in vertically positioned glass tubes. Here, the CdSe nanocrystals were aligned in a regular fcc. 3D superlattice.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD38XjtVKlsA%253D%253D&md5=3a22bf4d9d418c43a3e530275211edd5
  7. 7
    Bodnarchuk, M. I.; Kovalenko, M. V.; Heiss, W.; Talapin, D. V. Energetic and Entropic Contributions to Self-Assembly of Binary Nanocrystal Superlattices: Temperature as the Structure-Directing Factor. J. Am. Chem. Soc. 2010, 132, 11967– 11977,  DOI: 10.1021/ja103083q
    Google Scholar
    7
    Energetic and Entropic Contributions to Self-Assembly of Binary Nanocrystal Superlattices: Temperature as the Structure-Directing Factor
    Bodnarchuk, Maryna I.; Kovalenko, Maksym V.; Heiss, Wolfgang; Talapin, Dmitri V.
    Journal of the American Chemical Society (2010), 132 (34), 11967-11977CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
    We studied the effect of temp. on self-assembly of monodisperse colloidal nanocrystals into single-component and binary superlattices. Temp., which serves as a weighting factor for the internal energy (U) and entropy (S) contributions to the Helmholtz free energy F = U - TS, allows tailoring relative wts. of the interparticle interactions and free-vol. entropy during the formation of nanocrystal superlattices. Temp. also provides a convenient tool for directing self-assembly of nanocrystals toward desired superlattice structures. We found that temp. strongly affects the structures of binary superlattices self-assembled from the mixts. of CdSe + PbS nanocrystals and PbSe + Pd nanocrystals. In the former case, small Hamaker consts. for CdSe and PbS nanocrystals led to a relatively simple phase diagram, including only high-d. NaZn13-, AlB2-, and NaCl-type binary superlattices. In contrast, binary superlattices self-assembled at different temps. from PbSe and Pd nanocrystals showed a no. of low-d. complex phases stabilized by strong local van der Waals interactions between Pd nanocrystals. The structural diversity of nanoparticle superlattices is shown to be a result of the cooperative effect of the entropy-driven crystn. and the interparticle interactions. Both ΔU and TΔS terms assocd. with the superlattice formation should be of the same order of magnitude, with |ΔU| < |TΔS| for the assembly of CdSe and PbS nanocrystals and |ΔU| > |TΔS| for the PbSe and Pd nanocrystals.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhtVSisr%252FL&md5=78ef66124c481ece874d0ad5a8e93094
  8. 8
    Boles, M. A.; Talapin, D. V. Self-Assembly of Tetrahedral CdSe Nanocrystals: Effective ″Patchiness″ via Anisotropic Steric Interaction. J. Am. Chem. Soc. 2014, 136, 5868– 5871,  DOI: 10.1021/ja501596z
    Google Scholar
    8
    Self-Assembly of Tetrahedral CdSe Nanocrystals: Effective "Patchiness" via Anisotropic Steric Interaction
    Boles, Michael A.; Talapin, Dmitri V.
    Journal of the American Chemical Society (2014), 136 (16), 5868-5871CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
    Self-assembled superlattices (SLs) comprised of tetrahedral nanocrystal (NCs) are described. Self-assembly of CdSe nanotetrahedra into an open structure (estd. space-filling fraction φ ≈ 0.59) was obsd. This finding highlights a gap in the understanding of the hierarchy of energy scales acting on colloidal NCs during self-assembly. A strong dependence of ligand-ligand interaction potential on NC surface curvature is proposed. This effect favors spatial proximity of vertices in the dense colloidal crystal and may be considered an emergent "patchiness" acting through chem. identical ligand mols.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXkslals7g%253D&md5=0e75fe9e8b885d19708691a89c62c463
  9. 9
    Dong, A.; Chen, J.; Vora, P. M.; Kikkawa, J. M.; Murray, C. B. Binary Nanocrystal Superlattice Membranes Self-Assembled at the Liquid-Air Interface. Nature 2010, 466, 474– 477,  DOI: 10.1038/nature09188
    Google Scholar
    9
    Binary nanocrystal superlattice membranes self-assembled at the liquid-air interface
    Dong, Angang; Chen, Jun; Vora, Patrick M.; Kikkawa, James M.; Murray, Christopher B.
    Nature (London, United Kingdom) (2010), 466 (7305), 474-477CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)
    The spontaneous organization of multicomponent micrometer-sized colloids or nanocrystals into superlattices is of scientific importance for understanding the assembly process on the nanometer scale and is of great interest for bottom-up fabrication of functional devices. In particular, co-assembly of two types of nanocrystal into binary nanocrystal superlattices (BNSLs) has recently attracted significant attention, as this provides a low-cost, programmable way to design meta materials with precisely controlled properties that arise from the organization and interactions of the constituent nanocrystal components. Although challenging, the ability to grow and manipulate large-scale BNSLs is crit. for extensive exploration of this new class of material. The authors report a general method of growing centimeter-scale, uniform membranes of BNSLs that can readily be transferred to arbitrary substrates. The authors' method is based on the liq.-air interfacial assembly of multicomponent nanocrystals and circumvents the limitations assocd. with the current assembly strategies, allowing integration of BNSLs on any substrate for the fabrication of nanocrystal-based devices. The authors demonstrate the construction of magnetoresistive devices by incorporating large-area (1.5 mm × 2.5 mm) BNSL membranes; their magneto transport measurements clearly show that device magnetoresistance is dependent on the structure (stoichiometry) of the BNSLs. The ability to transfer BNSLs also allows the construction of free-standing membranes and other complex architectures that were not accessible previously.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXptFGqtbo%253D&md5=09dad42e48f5c7c4b24cdb093274d196
  10. 10
    Paik, T.; Yun, H.; Fleury, B.; Hong, S. H.; Jo, P. S.; Wu, Y.; Oh, S. J.; Cargnello, M.; Yang, H.; Murray, C. B.; Kagan, C. R. Hierarchical Materials Design by Pattern Transfer Printing of Self-Assembled Binary Nanocrystal Superlattices. Nano Lett. 2017, 17, 1387– 1394,  DOI: 10.1021/acs.nanolett.6b04279
    Google Scholar
    10
    Hierarchical Materials Design by Pattern Transfer Printing of Self-Assembled Binary Nanocrystal Superlattices
    Paik, Taejong; Yun, Hongseok; Fleury, Blaise; Hong, Sung-Hoon; Jo, Pil Sung; Wu, Yaoting; Oh, Soong-Ju; Cargnello, Matteo; Yang, Haoran; Murray, Christopher B.; Kagan, Cherie R.
    Nano Letters (2017), 17 (3), 1387-1394CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
    We demonstrate the fabrication of hierarchical materials by controlling the structure of highly ordered binary nanocrystal superlattices (BNSLs) on multiple length scales. Combinations of magnetic, plasmonic, semiconducting, and insulating colloidal nanocrystal (NC) building blocks are self-assembled into BNSL membranes via the liq.-interfacial assembly technique. Free-standing BNSL membranes are transferred onto topog. structured poly(dimethylsiloxane) molds via the Langmuir-Schaefer technique and then deposited in patterns onto substrates via transfer printing. BNSLs with different structural motifs are successfully patterned into various meso- and microstructures such as lines, circles, and even three-dimensional grids across large-area substrates. A combination of electron microscopy and grazing incidence small-angle X-ray scattering (GISAXS) measurements confirm the ordering of NC building blocks in meso- and micropatterned BNSLs. This technique demonstrates structural diversity in the design of hierarchical materials by assembling BNSLs from NC building blocks of different compn. and size by patterning BNSLs into various size and shape superstructures of interest for a broad range of applications.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhvFWlu78%253D&md5=ce4a22627022f8d5f2b145cadd36691e
  11. 11
    Ye, X.; Collins, J. E.; Kang, Y.; Chen, J.; Chen, D. T.; Yodh, A. G.; Murray, C. B. Morphologically Controlled Synthesis of Colloidal Upconversion Nanophosphors and Their Shape-Directed Self-Assembly. Proc. Natl. Acad. Sci. U. S. A. 2010, 107, 22430– 22435,  DOI: 10.1073/pnas.1008958107
    Google Scholar
    11
    Morphologically controlled synthesis of colloidal upconversion nanophosphors and their shape-directed self-assembly
    Ye, Xingchen; Collins, Joshua E.; Kang, Yijin; Chen, Jun; Chen, Daniel T. N.; Yodh, Arjun G.; Murray, Christopher B.
    Proceedings of the National Academy of Sciences of the United States of America (2010), 107 (52), 22430-22435, S22430/1-S22430/27CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)
    We report a one-pot chem. approach for the synthesis of highly monodisperse colloidal nanophosphors displaying bright upconversion luminescence under 980 nm excitation. This general method optimizes the synthesis with initial heating rates up to 100°/min generating a rich family of nanoscale building blocks with distinct morphologies (spheres, rods, hexagonal prisms, and plates) and upconversion emission tunable through the choice of rare earth dopants. Furthermore, we employ an interfacial assembly strategy to organize these nanocrystals (NCs) into superlattices over multiple length scales facilitating the NC characterization and enabling systematic studies of shape-directed assembly. The global and local ordering of these superstructures is programmed by the precise engineering of individual NC's size and shape. This dramatically improved nanophosphor synthesis together with insights from shape-directed assembly will advance the investigation of an array of emerging biol. and energy-related nanophosphor applications.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXkslSltQ%253D%253D&md5=a1ab89a080bae230cd4ac93a01807aa9
  12. 12
    Wang, P. P.; Qiao, Q.; Zhu, Y.; Ouyang, M. Colloidal Binary Supracrystals with Tunable Structural Lattices. J. Am. Chem. Soc. 2018, 140, 9095– 9098,  DOI: 10.1021/jacs.8b05643
    Google Scholar
    12
    Colloidal Binary Supracrystals with Tunable Structural Lattices
    Wang, Peng-peng; Qiao, Qiao; Zhu, Yimei; Ouyang, Min
    Journal of the American Chemical Society (2018), 140 (29), 9095-9098CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
    Colloidal binary supracrystals (SCs) possessing tunable and ordered assembly of two different types of functional nanoparticles (NPs) represent a unique class of artificial materials for both fundamental study and technol. applications, but related study has been limited due to substantial challenges in materials growth. Here we report the controlled growth of colloidal binary SCs consisting of Au and Fe3O4 NPs via an oil-in-water emulsion process. The size, stoichiometry, and lattice structure of the SCs can be broadly tuned by the growth parameters. Furthermore, our growth method is general and applicable to other NP building blocks to achieve various functional binary SCs. These as-grown free-standing binary SCs should therefore enable new test beds for exploring different nanoscale interactions ranging from the formation and stability of nanoscale binary phase to the emerging magneto-plasmonic coupling physics.
    >> More from SciFinder ®
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  13. 13
    de Nijs, B.; Dussi, S.; Smallenburg, F.; Meeldijk, J. D.; Groenendijk, D. J.; Filion, L.; Imhof, A.; van Blaaderen, A.; Dijkstra, M. Entropy-driven formation of large icosahedral colloidal clusters by spherical confinement. Nat. Mater. 2015, 14, 56– 60,  DOI: 10.1038/nmat4072
    Google Scholar
    13
    Entropy-driven formation of large icosahedral colloidal clusters by spherical confinement
    de Nijs, Bart; Dussi, Simone; Smallenburg, Frank; Meeldijk, Johannes D.; Groenendijk, Dirk J.; Filion, Laura; Imhof, Arnout; van Blaaderen, Alfons; Dijkstra, Marjolein
    Nature Materials (2015), 14 (1), 56-60CODEN: NMAACR; ISSN:1476-1122. (Nature Publishing Group)
    Icosahedral symmetry, which is not compatible with truly long-range order, can be found in many systems, such as liqs., glasses, at. clusters, quasicrystals, and virus-capsids. To obtain arrangements with a high degree of icosahedral order from tens of particles or more, interparticle attractive interactions are considered to be essential. The authors report that entropy and spherical confinement suffice for the formation of icosahedral clusters consisting of up to 100,000 particles. Specifically, by using real-space measurements on nanometer- and micrometer-sized colloids, as well as computer simulations, the authors show that tens of thousands of hard spheres compressed under spherical confinement spontaneously crystallize into icosahedral clusters that are entropically favored over the bulk face-centered cubic crystal structure. These findings provide insights into the interplay between confinement and crystn. and into how these are connected to the formation of icosahedral structures.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhsVCrtLfJ&md5=f3d69b41b0a61150dc3b03cc3c9d1945
  14. 14
    Yu, Y.; Yu, D.; Orme, C. A. Reversible, Tunable, Electric-Field Driven Assembly of Silver Nanocrystal Superlattices. Nano Lett. 2017, 17, 3862– 3869,  DOI: 10.1021/acs.nanolett.7b01323
    Google Scholar
    14
    Reversible, Tunable, Electric-Field Driven Assembly of Silver Nanocrystal Superlattices
    Yu, Yixuan; Yu, Dian; Orme, Christine A.
    Nano Letters (2017), 17 (6), 3862-3869CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
    Nanocrystal superlattices are typically fabricated by either solvent evapn. or destabilization methods that require long time periods to generate highly ordered structures. In this paper, we report for the first time the use of elec. fields to reversibly drive nanocrystal assembly into superlattices without changing solvent vol. or compn., and show that this method only takes 20 min to produce polyhedral colloidal crystals, which would otherwise need days or weeks. This method offers a way to control the lattice consts. and degree of preferential orientation for superlattices and can suppress the uniaxial superlattice contraction assocd. with solvent evapn. In situ small-angle X-ray scattering expts. indicated that nanocrystal superlattices were formed while solvated, not during drying.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXnvFChs7c%253D&md5=2b96e185d0c6f3f00a1f7788d89b248c
  15. 15
    Singh, G.; Chan, H.; Baskin, A.; Gelman, E.; Repnin, N.; Kral, P.; Klajn, R. Self-Assembly of Magnetite Nanocubes into Helical Superstructures. Science 2014, 345, 1149– 1153,  DOI: 10.1126/science.1254132
    Google Scholar
    15
    Self-assembly of magnetite nanocubes into helical superstructures
    Singh, Gurvinder; Chan, Henry; Baskin, Artem; Gelman, Elijah; Repnin, Nikita; Kral, Petr; Klajn, Rafal
    Science (Washington, DC, United States) (2014), 345 (6201), 1149-1153CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
    Organizing inorg. nanocrystals into complex architectures is challenging and typically relies on preexisting templates, such as properly folded DNA or polypeptide chains. We found that under carefully controlled conditions, cubic nanocrystals of magnetite self-assemble into arrays of helical superstructures in a template-free manner with >99% yield. Computer simulations revealed that the formation of helixes is detd. by the interplay of van der Waals and magnetic dipole-dipole interactions, Zeeman coupling, and entropic forces and can be attributed to spontaneous formation of chiral nanocube clusters. Neighboring helixes within their densely packed ensembles tended to adopt the same handedness to maximize packing, thus revealing a novel mechanism of symmetry breaking and chirality amplification.
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  16. 16
    Bishop, K. J.; Wilmer, C. E.; Soh, S.; Grzybowski, B. A. Nanoscale Forces and Their Uses in Self-Assembly. Small 2009, 5, 1600– 1630,  DOI: 10.1002/smll.200900358
    Google Scholar
    16
    Nanoscale forces and their uses in self-assembly
    Bishop, Kyle J. M.; Wilmer, Christopher E.; Soh, Siowling; Grzybowski, Bartosz A.
    Small (2009), 5 (14), 1600-1630CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)
    A review. The ability to assemble nanoscopic components into larger structures and materials depends crucially on the ability to understand in quant. detail and subsequently "engineer" the interparticle interactions. This Review provides a crit. examn. of the various interparticle forces (van der Waals, electrostatic, magnetic, mol., and entropic) that can be used in nanoscale self-assembly. For each type of interaction, the magnitude and the length scale are discussed, as well as the scaling with particle size and interparticle distance. In all cases, the discussion emphasizes characteristics unique to the nanoscale. These theor. considerations are accompanied by examples of recent exptl. systems, in which specific interaction types were used to drive nanoscopic self-assembly. Overall, this Review aims to provide a comprehensive yet easily accessible resource of nanoscale-specific interparticle forces that can be implemented in models or simulations of self-assembly processes at this scale.
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  17. 17
    Murray, C. B.; Kagan, C. R.; Bawendi, M. G. Self-Organization of CdSe Nanocrystallites into Three-Dimensional Quantum Dot Superlattices. Science 1995, 270, 1335– 1338,  DOI: 10.1126/science.270.5240.1335
    Google Scholar
    17
    Self-organization of CdSe nanocrystallites into three-dimensional quantum dot superlattices
    Murray, C. B.; Kagan, C. R.; Bawendi, M. G.
    Science (Washington, D. C.) (1995), 270 (5240), 1335-8CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
    The self-organization of CdSe nanocrystallites into three-dimensional semiconductor quantum dot superlattices (colloidal crystals) is demonstrated. The size and spacing of the dots within the superlattice are controlled with near at. precision. This control is a result of synthetic advances that provide CdSe nanocrystallites that are monodisperse within the limit of at. roughness. The methodol. is not limited to semiconductor quantum dots but provides general procedures for the prepn. and characterization of ordered structures of nanocrystallites from a variety of materials.
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  18. 18
    Shevchenko, E. V.; Talapin, D. V.; Kotov, N. A.; O’Brien, S.; Murray, C. B. Structural Diversity in Binary Nanoparticle Superlattices. Nature 2006, 439, 55– 59,  DOI: 10.1038/nature04414
    Google Scholar
    18
    Structural diversity in binary nanoparticle superlattices
    Shevchenko, Elena V.; Talapin, Dmitri V.; Kotov, Nicholas A.; O'Brien, Stephen; Murray, Christopher B.
    Nature (London, United Kingdom) (2006), 439 (7072), 55-59CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)
    Assembly of small building blocks such as atoms, mols. and nanoparticles into macroscopic structures-i.e., 'bottom up' assembly-is a theme that runs through chem., biol. and material science. Bacteria, macromols. and nanoparticles can self-assemble, generating ordered structures with a precision that challenges current lithog. techniques. The assembly of nanoparticles of two different materials into a binary nanoparticle superlattice (BNSL) can provide a general and inexpensive path to a large variety of materials (metamaterials) with precisely controlled chem. compn. and tight placement of the components. Maximization of the nanoparticle packing d. is proposed as the driving force for BNSL formation, and only a few BNSL structures were predicted to be thermodynamically stable. Recently, colloidal crystals with micrometre-scale lattice spacings were grown from oppositely charged polymethyl methacrylate spheres. Here the authors demonstrate formation of >15 different BNSL structures, using combinations of semiconducting, metallic and magnetic nanoparticle building blocks. At least ten of these colloidal cryst. structures were not reported previously. Elec. charges on sterically stabilized nanoparticles det. BNSL stoichiometry; addnl. contributions from entropic, van der Waals, steric and dipolar forces stabilize the variety of BNSL structures.
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  19. 19
    Boles, M. A.; Talapin, D. V. Many-Body Effects in Nanocrystal Superlattices: Departure from Sphere Packing Explains Stability of Binary Phases. J. Am. Chem. Soc. 2015, 137, 4494– 4502,  DOI: 10.1021/jacs.5b00839
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    19
    Many-Body Effects in Nanocrystal Superlattices: Departure from Sphere Packing Explains Stability of Binary Phases
    Boles, Michael A.; Talapin, Dmitri V.
    Journal of the American Chemical Society (2015), 137 (13), 4494-4502CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
    This work analyzes the role of hydrocarbon ligands in the self-assembly of nanocrystal (NC) superlattices. Typical NCs, composed of an inorg. core of radius R and a layer of capping ligands with length L, can be described as soft spheres with softness parameter L/R. Using particle tracking measurements of TEM images, close-packed NCs, like their hard-sphere counterparts, fill space at ∼74% d. independent of softness. The authors uncover deformability of the ligand capping layer that leads to variable effective NC size in response to the coordination environment. This effect plays an important role in the packing of particles in binary nanocrystal superlattices (BNSLs). Measurements on BNSLs composed of NCs of varying softness in several coordination geometries indicate that NCs deform to produce dense BNSLs that would otherwise be low-d. arrangements if the particles remained spherical. Consequently, rationalizing the mixing of 2 NC species during BNSL self-assembly need not employ complex energetic interactions. The authors summarize the anal. in a set of packing rules. These findings contribute to a general understanding of entropic effects during crystn. of deformable objects (e.g., nanoparticles, micelles, globular proteins) that can adapt their shape to the local coordination environment.
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  20. 20
    Coropceanu, I.; Boles, M. A.; Talapin, D. V. Systematic Mapping of Binary Nanocrystal Superlattices: The Role of Topology in Phase Selection. J. Am. Chem. Soc. 2019, 141, 5728– 5740,  DOI: 10.1021/jacs.8b12539
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    20
    Systematic Mapping of Binary Nanocrystal Superlattices: The Role of Topology in Phase Selection
    Coropceanu, Igor; Boles, Michael A.; Talapin, Dmitri V.
    Journal of the American Chemical Society (2019), 141 (14), 5728-5740CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
    The self-assembly of two sizes of spherical nanocrystals has revealed a surprisingly diverse library of structures. To date, at least 15 distinct binary nanocrystal superlattice (BNSL) structures have been identified. The stability of these binary phases cannot be fully explained using the traditional conceptual framework treating the assembly process as entropy-driven crystn. of rigid spherical particles. Such deviation from hard sphere behavior may be explained by the soft and deformable layer of ligands that envelops the nanocrystals, which contributes significantly to the overall size and shape of assembling particles. In this work, we describe a set of expts. designed to elucidate the role of the ligand corona in shaping the thermodn. and kinetics of BNSL assembly. Using hydrocarbon-capped Au and PbS nanocrystals as a model binary system, we systematically tuned the core radius (R) and ligand chain length (L) of particles and subsequently assembled them into binary superlattices. The resulting database of binary structures enabled a detailed anal. of the role of effective nanocrystal size ratio, as well as softness expressed as L/R, in directing the assembly of binary structures. This catalog of superlattices allowed us to not only study the frequency of different phases but to also systematically measure the geometric parameters of the BNSLs. This anal. allowed us to evaluate new theor. models treating the cocrystn. of deformable spheres and to formulate new hypotheses about the factors affecting the nucleation and growth of the binary superlattices. Among other insights, our results suggest that the relative abundance of the binary phases obsd. may be explained not only by considerations of thermodn. stability, but also by a postulated preordering of the binary fluid into local structures with icosahedral or polytetrahedral symmetry prior to nucleation.
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  21. 21
    Landman, U.; Luedtke, W. D. Small Is Different: Energetic, Structural, Thermal, and Mechanical Properties of Passivated Nanocluster Assemblies. Faraday Discuss. 2004, 125, 1– 22,  DOI: 10.1039/b312640b
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    21
    Small is different: energetic, structural, thermal, and mechanical properties of passivated nanocluster assemblies
    Landman Uzi; Luedtke W D
    Faraday discussions (2004), 125 (), 1-22; discussion 99-116 ISSN:1359-6640.
    We explore, with the use of extensive molecular dynamics simulations, several principal issues pertaining to the energetics of formation of superlattices made through the assembly of passivated nanoclusters, the interactions that underlie the cohesion of such superlattices, and the unique mechanical, thermal and structural properties that they exhibit. Our investigations focus on assemblies made of crystalline gold nanoclusters of variable sizes, passivated by monolayers of alkylthiol molecules. An analytic optimal packing model that correlates in a unified manner several structural characteristics of three-dimensional superlattice assemblies is developed. The model successfully organizes and systematizes a large amount of experimental and simulation data, and it predicts the phase-boundary between different superlattice structural motifs that evolve as a function of the ratio between the chain-length of the extended passivating molecules and the radius of the underlying gold nanocluster. The entropic contribution to the formation free energy of the superlattice assembly is found to be large and of similar magnitude as the potential energy component of the free energy. The major contribution to the cohesive potential energy of the superlattice is shown to originate from van der Waals interactions between molecules that passivate neighboring nanoclusters. The unique mechanical, thermal, thermomechanical, and thermostructural properties of passivated nanocluster assemblies, are discussed.
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  22. 22
    Deng, K.; Luo, Z.; Tan, L.; Quan, Z. Self-Assembly of Anisotropic Nanoparticles into Functional Superstructures. Chem. Soc. Rev. 2020, 49, 6002– 6038,  DOI: 10.1039/D0CS00541J
    Google Scholar
    22
    Self-assembly of anisotropic nanoparticles into functional superstructures
    Deng, Kerong; Luo, Zhishan; Tan, Li; Quan, Zewei
    Chemical Society Reviews (2020), 49 (16), 6002-6038CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
    A review. Self-assembly of colloidal nanoparticles (NPs) into superstructures offers a flexible and promising pathway to manipulate the nanometer-sized particles and thus make full use of their unique properties. This bottom-up strategy builds a bridge between the NP regime and a new class of transformative materials across multiple length scales for technol. applications. In this field, anisotropic NPs with size- and shape-dependent phys. properties as self-assembly building blocks have long fascinated scientists. Self-assembly of anisotropic NPs not only opens up exciting opportunities to engineer a variety of intriguing and complex superlattice architectures, but also provides access to discover emergent collective properties that stem from their ordered arrangement. Thus, this has stimulated enormous research interests in both fundamental science and technol. applications. This present review comprehensively summarizes the latest advances in this area, and highlights their rich packing behaviors from the viewpoint of NP shape. We provide the basics of the exptl. techniques to produce NP superstructures and structural characterization tools, and detail the delicate assembled structures. Then the current understanding of the assembly dynamics is discussed with the assistance of in situ studies, followed by emergent collective properties from these NP assemblies. Finally, we end this article with the remaining challenges and outlook, hoping to encourage further research in this field.
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  23. 23
    Glotzer, S. C.; Solomon, M. J. Anisotropy of Building Blocks and Their Assembly into Complex Structures. Nat. Mater. 2007, 6, 557– 562,  DOI: 10.1038/nmat1949
    Google Scholar
    23
    Anisotropy of building blocks and their assembly into complex structures
    Glotzer Sharon C; Solomon Michael J
    Nature materials (2007), 6 (8), 557-62 ISSN:1476-1122.
    A revolution in novel nanoparticles and colloidal building blocks has been enabled by recent breakthroughs in particle synthesis. These new particles are poised to become the 'atoms' and 'molecules' of tomorrow's materials if they can be successfully assembled into useful structures. Here, we discuss the recent progress made in the synthesis of nanocrystals and colloidal particles and draw analogies between these new particulate building blocks and better-studied molecules and supramolecular objects. We argue for a conceptual framework for these new building blocks based on anisotropy attributes and discuss the prognosis for future progress in exploiting anisotropy for materials design and assembly.
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  24. 24
    Millan, J. A.; Ortiz, D.; van Anders, G.; Glotzer, S. C. Self-Assembly of Archimedean Tilings with Enthalpically and Entropically Patchy Polygons. ACS Nano 2014, 8, 2918– 2928,  DOI: 10.1021/nn500147u
    Google Scholar
    24
    Self-Assembly of Archimedean Tilings with Enthalpically and Entropically Patchy Polygons
    Millan, Jaime A.; Ortiz, Daniel; van Anders, Greg; Glotzer, Sharon C.
    ACS Nano (2014), 8 (3), 2918-2928CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
    Exptl. accessible, rational design rules for the self-assembly of the Archimedean tilings from polygonal nanoplates are presented. The Archimedean tilings represent a model set of target patterns that (i) contain both simple and complex patterns, (ii) are comprised of simple regular shapes, and (iii) contain patterns with potentially interesting materials properties. Via Monte Carlo simulations, the authors propose a set of design rules with general applicability to one- and two-component systems of polygons. These design rules, specified by increasing levels of patchiness, correspond to a reduced set of anisotropy dimensions for robust self-assembly of the Archimedean tilings. The authors show for which tilings entropic patches alone are sufficient for assembly and when short-range enthalpic interactions are required. For the latter, we show how patchy these interactions should be for optimal yield. This study provides a minimal set of guidelines for the design of anisotropic patchy particles that can self-assemble all 11 Archimedean tilings.
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  25. 25
    van Anders, G.; Klotsa, D.; Ahmed, N. K.; Engel, M.; Glotzer, S. C. Understanding Shape Entropy through Local Dense Packing. Proc. Natl. Acad. Sci. U. S. A. 2014, 111, E4812– E4821,  DOI: 10.1073/pnas.1418159111
    Google Scholar
    25
    Understanding shape entropy through local dense packing
    van Anders, Greg; Klotsa, Daphne; Ahmed, N. Khalid; Engel, Michael; Glotzer, Sharon C.
    Proceedings of the National Academy of Sciences of the United States of America (2014), 111 (45), E4812-E4821CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)
    Entropy drives the phase behavior of colloids ranging from dense suspensions of hard spheres or rods to dil. suspensions of hard spheres and depletants. Entropic ordering of anisotropic shapes into complex crystals, liq. crystals, and even quasicrystals was demonstrated recently in computer simulations and expts. The ordering of shapes appears to arise from the emergence of directional entropic forces (DEFs) that align neighboring particles, but these forces were neither rigorously defined nor quantified in generic systems. Here, the authors show quant. that shape drives the phase behavior of systems of anisotropic particles upon crowding through DEFs. The authors define DEFs in generic systems and compute them for several hard particle systems. The authors show they are on the order of a few times the thermal energy (kBT) at the onset of ordering, placing DEFs on par with traditional depletion, van der Waals, and other intrinsic interactions. In exptl. systems with these other interactions, the authors provide direct quant. evidence that entropic effects of shape also contribute to self-assembly. The authors use DEFs to draw a distinction between self-assembly and packing behavior. The mechanism that generates directional entropic forces is the maximization of entropy by optimizing local particle packing. This mechanism occurs in a wide class of systems and the authors treat, in a unified way, the entropy-driven phase behavior of arbitrary shapes, incorporating the known works of Kirkwood, Onsager, and Asakura and Oosawa.
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  26. 26
    Demortiere, A.; Launois, P.; Goubet, N.; Albouy, P. A.; Petit, C. Shape-Controlled Platinum Nanocubes and Their Assembly into Two-Dimensional and Three-Dimensional Superlattices. J. Phys. Chem. B 2008, 112, 14583– 14592,  DOI: 10.1021/jp802081n
    Google Scholar
    26
    Shape-Controlled Platinum Nanocubes and Their Assembly into Two-Dimensional and Three-Dimensional Superlattices
    Demortiere, A.; Launois, P.; Goubet, N.; Albouy, P.-A.; Petit, C.
    Journal of Physical Chemistry B (2008), 112 (46), 14583-14592CODEN: JPCBFK; ISSN:1520-6106. (American Chemical Society)
    Liq.-liq. phase transfer was used to synthesize platinum nanocrystals with a cubic morphol. By finely tuning the parameters controlling the nucleation and growth processes, nanometric truncated cubes or perfect cubes may be obtained. This is the 1st time such shapes are obtained with this procedure. The importance of both the length of the capping agent to control the growth process and the bromide anions as poison for the {111} facet is shown. The low degree of size polydispersity allows these nanocrystals to self-assemble with a long-range ordering in two-dimensional and three-dimensional supracrystals. According to the nanocrystal shape, simple cubic or fcc. supracrystals are obsd. It is remarkable to notice that well-faceted supracrystals with sizes ∼10 μm may be obtained.
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  27. 27
    Quan, Z.; Loc, W. S.; Lin, C.; Luo, Z.; Yang, K.; Wang, Y.; Wang, H.; Wang, Z.; Fang, J. Tilted Face-Centered-Cubic Supercrystals of PbS Nanocubes. Nano Lett. 2012, 12, 4409– 4413,  DOI: 10.1021/nl302324b
    Google Scholar
    27
    Tilted face-centered-cubic supercrystals of PbS nanocubes
    Quan, Zewei; Loc, Welley Siu; Lin, Cuikun; Luo, Zhiping; Yang, Kaikun; Wang, Yuxuan; Wang, Howard; Wang, Zhongwu; Fang, Jiye
    Nano Letters (2012), 12 (8), 4409-4413CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
    We demonstrate a direct fabrication of PbS nanocube supercrystals without size-selection pretreatment on the building blocks. Electron microscopic and synchrotron small angle X-ray scattering analyses confirm that nanocubes pack through a tilted face-centered-cubic (fcc) arrangement, i.e., face-to-face along the 〈110〉super direction, resulting in a real packing efficiency of as high as ∼83%. This new type of superstructure consisting of nanocubes as building blocks, reported here for the first time, is considered the most stable surfactant-capped nanocube superstructure detd. by far.
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  28. 28
    Disch, S.; Wetterskog, E.; Hermann, R. P.; Salazar-Alvarez, G.; Busch, P.; Bruckel, T.; Bergstrom, L.; Kamali, S. Shape Induced Symmetry in Self-Assembled Mesocrystals of Iron Oxide Nanocubes. Nano Lett. 2011, 11, 1651– 1656,  DOI: 10.1021/nl200126v
    Google Scholar
    28
    Shape Induced Symmetry in Self-Assembled Mesocrystals of Iron Oxide Nanocubes
    Disch, Sabrina; Wetterskog, Erik; Hermann, Raphaeel P.; Salazar-Alvarez, German; Busch, Peter; Brueckel, Thomas; Bergstroem, Lennart; Kamali, Saeed
    Nano Letters (2011), 11 (4), 1651-1656CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
    Grazing incidence small-angle scattering and electron microscopy have been used to show for the first time that nonspherical nanoparticles can assemble into highly ordered body-centered tetragonal mesocrystals. Energy models accounting for the directionality and magnitude of the van der Waals and dipolar interactions as a function of the degree of truncation of the nanocubes illustrated the importance of the directional dipolar forces for the formation of the initial nanocube clusters and the dominance of the van der Waals multibody interactions in the dense packed arrays.
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  29. 29
    Disch, S.; Wetterskog, E.; Hermann, R. P.; Korolkov, D.; Busch, P.; Boesecke, P.; Lyon, O.; Vainio, U.; Salazar-Alvarez, G.; Bergstrom, L.; Bruckel, T. Structural Diversity in Iron Oxide Nanoparticle Assemblies as Directed by Particle Morphology and Orientation. Nanoscale 2013, 5, 3969– 3975,  DOI: 10.1039/c3nr33282a
    Google Scholar
    29
    Structural diversity in iron oxide nanoparticle assemblies as directed by particle morphology and orientation
    Disch, Sabrina; Wetterskog, Erik; Hermann, Raphael P.; Korolkov, Denis; Busch, Peter; Boesecke, Peter; Lyon, Olivier; Vainio, Ulla; Salazar-Alvarez, German; Bergstroem, Lennart; Brueckel, Thomas
    Nanoscale (2013), 5 (9), 3969-3975CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)
    The mesostructure of ordered arrays of anisotropic nanoparticles is controlled by a combination of packing constraints and interparticle interactions, two factors that are strongly dependent on the particle morphol. We have investigated how the degree of truncation of iron oxide nanocubes controls the mesostructure and particle orientation in drop cast mesocrystal arrays. The combination of grazing incidence small-angle X-ray scattering and SEM shows that mesocrystals of highly truncated cubic nanoparticles assemble in an fcc-type mesostructure, similar to arrays formed by iron oxide nanospheres, but with a significantly reduced packing d. and displaying two different growth orientations. Strong satellite reflections in the GISAXS pattern indicate a commensurate mesoscopic superstructure that is related to stacking faults in mesocrystals of the anisotropic nanocubes. Our results show how subtle variation in shape anisotropy can induce oriented arrangements of nanoparticles of different structures and also create mesoscopic superstructures of larger periodicity.
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  30. 30
    Sanchez-Iglesias, A.; Grzelczak, M.; Perez-Juste, J.; Liz-Marzan, L. M. Binary Self-Assembly of Gold Nanowires with Nanospheres and Nanorods. Angew. Chem., Int. Ed. Engl. 2010, 49, 9985– 9989,  DOI: 10.1002/anie.201005891
    Google Scholar
    30
    Binary self-assembly of gold nanowires with nanospheres and nanorods
    Sanchez-Iglesias Ana; Grzelczak Marek; Perez-Juste Jorge; Liz-Marzan Luis M
    Angewandte Chemie (International ed. in English) (2010), 49 (51), 9985-9 ISSN:.
    There is no expanded citation for this reference.
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  31. 31
    Paik, T.; Ko, D. K.; Gordon, T. R.; Doan-Nguyen, V.; Murray, C. B. Studies of Liquid Crystalline Self-Assembly of GdF3 Nanoplates by In-Plane, Out-of-Plane SAXS. ACS Nano 2011, 5, 8322– 8330,  DOI: 10.1021/nn203049t
    Google Scholar
    31
    Studies of Liquid Crystalline Self-Assembly of GdF3 Nanoplates by In-Plane, Out-of-Plane SAXS
    Paik, Taejong; Ko, Dong-Kyun; Gordon, Thomas R.; Doan-Nguyen, Vicky; Murray, Christopher B.
    ACS Nano (2011), 5 (10), 8322-8330CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
    Directed self-assembly of colloidal nanocrystals into ordered superlattices enables the prepn. of novel metamaterials with diverse functionalities. Structural control and precise characterization of these superlattices allow the interactions between individual nanocrystal building blocks and the origin of their collective properties to be understood. Here, the authors report the directed liq. interfacial assembly of gadolinium trifluoride (GdF3) nanoplates into liq. cryst. assemblies displaying long-range orientational and positional order. The macroscopic orientation of superlattices is controlled by changing the subphases upon which liq. interfacial assembly occurs. The assembled structures are characterized by a combination of TEM and small-angle x-ray scattering (SAXS) measurements performed on a lab. diffractometer. By doping GdF3 nanoplates with europium (Eu3+), luminescent phosphorescent superlattices with controlled structure are produced and enable detailed structural and optical characterization.
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  32. 32
    Nagaoka, Y.; Wang, T.; Lynch, J.; LaMontagne, D.; Cao, Y. C. Binary Assembly of Colloidal Semiconductor Nanorods with Spherical Metal Nanoparticles. Small 2012, 8, 843– 846,  DOI: 10.1002/smll.201101902
    Google Scholar
    32
    Binary Assembly of Colloidal Semiconductor Nanorods with Spherical Metal Nanoparticles
    Nagaoka, Yasutaka; Wang, Tie; Lynch, Jared; LaMontagne, Derek; Cao, Y. Charles
    Small (2012), 8 (6), 843-846CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)
    To explore the possibility of overcoming entropically and energetically unfavorable interactions which is crit. for the formation of binary assemblies of colloidal nanorods with nanospheres, we used colloidal CdSe/CdS semiconductor nanorods and spherical gold nanoparticles as a model system. Using literature methods, the authors synthesized octadecylphosphonate-functionalized CdSe/CdS nanorods and dodecanethiol (DDT)-capped gold nanoparticles. Since gold exhibits a very large Hamaker const., we originally hypothesized that the strong van der Waals (vdW) attraction between CdSe/CdS nanorods and gold nanoparticles would prevent the phase sepn. of these two building blocks. However, our exptl. results show that the use of triphenylphosphine (TPP) as an additive is important to the formation of binary assemblies of CdSe/CdS nanorods with gold nanoparticles. The results from our mechanistic studies suggest that the formation of these binary assemblies is a kinetically limited process, in which suitable additives and spherical nanoparticles with a high dielec. const. and a large Hamaker const. play important roles.
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  33. 33
    Ye, X.; Millan, J. A.; Engel, M.; Chen, J.; Diroll, B. T.; Glotzer, S. C.; Murray, C. B. Shape Alloys of Nanorods and Nanospheres from Self-Assembly. Nano Lett. 2013, 13, 4980– 4988,  DOI: 10.1021/nl403149u
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    33
    Shape Alloys of Nanorods and Nanospheres from Self-Assembly
    Ye, Xingchen; Millan, Jaime A.; Engel, Michael; Chen, Jun; Diroll, Benjamin T.; Glotzer, Sharon C.; Murray, Christopher B.
    Nano Letters (2013), 13 (10), 4980-4988CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
    Mixts. of anisotropic nanocrystals promise a great diversity of superlattices and phase behaviors beyond those of single-component systems. However, obtaining a colloidal shape alloy in which two different shapes are thermodynamically co-assembled into a cryst. superlattice has remained a challenge. The authors present a joint exptl.-computational investigation of two geometrically ubiquitous nanocryst. building blocks - nanorods and nanospheres - that overcome their natural entropic tendency toward macroscopic phase sepn. and co-assemble into three intriguing phases over centimeter scales, including an AB2-type binary superlattice. Monte Carlo simulations reveal that, although this shape alloy is entropically stable at high packing fraction, demixing is favored at exptl. densities. Simulations with short-ranged attractive interactions demonstrate that the alloy is stabilized by interactions induced by ligand stabilizers and/or depletion effects. An asymmetry in the relative interaction strength between rods and spheres improves the robustness of the self-assembly process.
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  34. 34
    Ming, T.; Kou, X.; Chen, H.; Wang, T.; Tam, H. L.; Cheah, K. W.; Chen, J. Y.; Wang, J. Ordered Gold Nanostructure Assemblies Formed by Droplet Evaporation. Angew. Chem., Int. Ed. Engl. 2008, 47, 9685– 9690,  DOI: 10.1002/anie.200803642
    Google Scholar
    34
    Ordered gold nanostructure assemblies formed by droplet evaporation
    Ming Tian; Kou Xiaoshan; Chen Huanjun; Wang Tao; Tam Hoi-Lam; Cheah Kok-Wai; Chen Ji-Yao; Wang Jianfang
    Angewandte Chemie (International ed. in English) (2008), 47 (50), 9685-90 ISSN:.
    There is no expanded citation for this reference.
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  35. 35
    Castelli, A.; de Graaf, J.; Prato, M.; Manna, L.; Arciniegas, M. P. Tic-Tac-Toe Binary Lattices from the Interfacial Self-Assembly of Branched and Spherical Nanocrystals. ACS Nano 2016, 10, 4345– 4353,  DOI: 10.1021/acsnano.5b08018
    Google Scholar
    35
    Tic-Tac-Toe Binary Lattices from the Interfacial Self-Assembly of Branched and Spherical Nanocrystals
    Castelli, Andrea; de Graaf, Joost; Prato, Mirko; Manna, Liberato; Arciniegas, Milena P.
    ACS Nano (2016), 10 (4), 4345-4353CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
    The self-organization of nanocrystals has proven to be a versatile route to achieve increasingly sophisticated structures of materials, where the shape and properties of individual particles impact the final functionalities. Recent works have addressed this topic by combining various shapes to achieve more complex arrangements of particles than are possible in single-component samples. However, the ability to create intricate architectures over large regions by exploiting the shape of multiply branched nanocrystals to host a second component remains unexplored. Here, we show how the concave shape of a branched nanocrystal, the so-called octapod, is able to anchor a sphere. The two components self-assemble into a locally ordered monolayer consisting of an intercalated square lattice of octapods and spheres, which is reminiscent of the "tic-tac-toe" game. These tic-tac-toe domains form through an interfacial self-assembly that occurs by the dewetting of a hexane layer contg. both particle types. By varying the exptl. conditions and performing mol. dynamics simulations, we show that the ligands coating the octapods are crucial to the formation of this structure. We find that the tendency of an octapod to form an interlocking-type structure with a second octapod strongly depends on the ligand shell of the pods. Breaking this tendency by ligand exchange allows the octapods to assemble into a more relaxed configuration, which is able to form a lock-and-key-type structure with a sphere, when they have a suitable size ratio. Our findings provide an example of a more versatile use of branched nanocrystals in self-assembled functional materials.
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  36. 36
    Paik, T.; Murray, C. B. Shape-Directed Binary Assembly of Anisotropic Nanoplates: A Nanocrystal Puzzle with Shape-Complementary Building Blocks. Nano Lett. 2013, 13, 2952– 2956,  DOI: 10.1021/nl401370n
    Google Scholar
    36
    Shape-Directed Binary Assembly of Anisotropic Nanoplates: A Nanocrystal Puzzle with Shape-Complementary Building Blocks
    Paik, Taejong; Murray, Christopher B.
    Nano Letters (2013), 13 (6), 2952-2956CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
    The authors present the binary self-assembly of two anisotropic nanoplate building blocks mediated by shape complementarity. The authors use rhombic GdF3 and tripodal Gd2O3 nanoplates as building blocks in which the size and shape are designed to be optimal for complementary organization. A liq. interfacial assembly technique gave self-assembled binary superlattices from two anisotropic nanoplates over a micrometer length scale. Shape-directed self-assembly guides the position of each anisotropic nanoplate in the binary superlattices, allowing for long-range orientational and positional order of each building block. The design of shape complementary anisotropic building blocks offers the possibility to self-assemble binary superlattices with predictable and designable structures.
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  37. 37
    Paik, T.; Diroll, B. T.; Kagan, C. R.; Murray, C. B. Binary and Ternary Superlattices Self-Assembled from Colloidal Nanodisks and Nanorods. J. Am. Chem. Soc. 2015, 137, 6662– 6669,  DOI: 10.1021/jacs.5b03234
    Google Scholar
    37
    Binary and Ternary Superlattices Self-Assembled from Colloidal Nanodisks and Nanorods
    Paik, Taejong; Diroll, Benjamin T.; Kagan, Cherie R.; Murray, Christopher B.
    Journal of the American Chemical Society (2015), 137 (20), 6662-6669CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
    The formation of binary and ternary superlattices from colloidal two-dimensional LaF3 nanodisks and one-dimensional CdSe/CdS nanorods was achieved via liq. interfacial assembly. The colloidal nanodisks and nanorods are coassembled into AB-, AB2-, and AB6-type binary arrays detd. by their relative size ratio and concn. to maximize their packing d. The position and orientation of anisotropic nanocrystal building blocks are tightly controlled in the self-assembled binary and ternary lattices. The macroscopic orientation of the superlattices is further tuned by changing the liq. subphase used for self-assembly, resulting in the formation of lamellar-type binary liq. cryst. superlattices. A ternary superlattice was self-assembled from two different sizes of nanodisks and a nanorod, which offers the unique opportunity to design multifunctional metamaterials.
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  38. 38
    Elbert, K. C.; Zygmunt, W.; Vo, T.; Vara, C. M.; Rosen, D. J.; Krook, N. M.; Glotzer, S. C.; Murray, C. B. Anisotropic Nanocrystal Shape and Ligand Design for Co-Assembly. Sci. Adv. 2021, 7, eabf9402  DOI: 10.1126/sciadv.abf9402
    Google Scholar
    There is no corresponding record for this reference.
  39. 39
    Protesescu, L.; Yakunin, S.; Bodnarchuk, M. I.; Krieg, F.; Caputo, R.; Hendon, C. H.; Yang, R. X.; Walsh, A.; Kovalenko, M. V. Nanocrystals of Cesium Lead Halide Perovskites (CsPbX3, X = Cl, Br, and I): Novel Optoelectronic Materials Showing Bright Emission with Wide Color Gamut. Nano Lett. 2015, 15, 3692– 3696,  DOI: 10.1021/nl5048779
    Google Scholar
    39
    Nanocrystals of Cesium Lead Halide Perovskites (CsPbX3, X = Cl, Br, and I): Novel Optoelectronic Materials Showing Bright Emission with Wide Color Gamut
    Protesescu, Loredana; Yakunin, Sergii; Bodnarchuk, Maryna I.; Krieg, Franziska; Caputo, Riccarda; Hendon, Christopher H.; Yang, Ruo Xi; Walsh, Aron; Kovalenko, Maksym V.
    Nano Letters (2015), 15 (6), 3692-3696CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
    Metal halides perovskites, such as hybrid org.-inorg. MeNH3PbI3, are newcomer optoelectronic materials that have attracted enormous attention as soln.-deposited absorbing layers in solar cells with power conversion efficiencies reaching 20%. A new avenue for halide perovskites was demonstrated by designing highly luminescent perovskite-based colloidal quantum dot materials. Monodisperse colloidal nanocubes (4-15 nm edge lengths) of fully inorg. perovskites (CsPbX3, X = Cl, Br, and I or mixed halide systems Cl/Br and Br/I) were synthesized using inexpensive com. precursors. Through compositional modulations and quantum size-effects, the bandgap energies and emission spectra are readily tunable over the entire visible spectral region of 410-700 nm. The luminescence of CsPbX3 nanocrystals is characterized by narrow emission line-widths of 12-42 nm, wide color gamut covering up to 140% of the NTSC color std., high quantum yields of ≤90%, and radiative lifetimes at 1-29 ns. The compelling combination of enhanced optical properties and chem. robustness makes CsPbX3 nanocrystals appealing for optoelectronic applications, particularly for blue and green spectral regions (410-530 nm), where typical metal chalcogenide-based quantum dots suffer from photodegrdn.
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  40. 40
    Kovalenko, M. V.; Protesescu, L.; Bodnarchuk, M. I. Properties and Potential Optoelectronic Applications of Lead Halide Perovskite Nanocrystals. Science 2017, 358, 745– 750,  DOI: 10.1126/science.aam7093
    Google Scholar
    40
    Properties and potential optoelectronic applications of lead halide perovskite nanocrystals
    Kovalenko, Maksym V.; Protesescu, Loredana; Bodnarchuk, Maryna I.
    Science (Washington, DC, United States) (2017), 358 (6364), 745-750CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
    A review. Semiconducting lead halide perovskites (LHPs) have not only become prominent thin-film absorber materials in photovoltaics but have also proven to be disruptive in the field of colloidal semiconductor nanocrystals (NCs). The most important feature of LHP NCs is their so-called defect-tolerance-the apparently benign nature of structural defects, highly abundant in these compds., with respect to optical and electronic properties. Here, we review the important differences that exist in the chem. and physics of LHP NCs as compared with more conventional, tetrahedrally bonded, elemental, and binary semiconductor NCs (such as silicon, germanium, cadmium selenide, gallium arsenide, and indium phosphide). We survey the prospects of LHP NCs for optoelectronic applications such as in television displays, light-emitting devices, and solar cells, emphasizing the practical hurdles that remain to be overcome.
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  41. 41
    Akkerman, Q. A.; Rainò, G.; Kovalenko, M. V.; Manna, L. Genesis, Challenges and Opportunities for Colloidal Lead Halide Perovskite Nanocrystals. Nat. Mater. 2018, 17, 394– 405,  DOI: 10.1038/s41563-018-0018-4
    Google Scholar
    41
    Genesis, challenges and opportunities for colloidal lead halide perovskite nanocrystals
    Akkerman, Quinten A.; Raino, Gabriele; Kovalenko, Maksym V.; Manna, Liberato
    Nature Materials (2018), 17 (5), 394-405CODEN: NMAACR; ISSN:1476-1122. (Nature Research)
    A review. Lead halide perovskites (LHPs) in the form of nanometer-sized colloidal crystals, or nanocrystals (NCs), have attracted the attention of diverse materials scientists due to their unique optical versatility, high photoluminescence quantum yields and facile synthesis. LHP NCs have a 'soft' and predominantly ionic lattice, and their optical and electronic properties are highly tolerant to structural defects and surface states. Therefore, they cannot be approached with the same exptl. mindset and theor. framework as conventional semiconductor NCs. In this Review, we discuss LHP NCs historical and current research pursuits, challenges in applications, and the related present and future mitigation strategies explored.
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  42. 42
    Dey, A.; Ye, J.; De, A.; Debroye, E.; Ha, S. K.; Bladt, E.; Kshirsagar, A. S.; Wang, Z.; Yin, J.; Wang, Y.; Quan, L. N.; Yan, F.; Gao, M.; Li, X.; Shamsi, J.; Debnath, T.; Cao, M.; Scheel, M. A.; Kumar, S.; Steele, J. A.; Gerhard, M.; Chouhan, L.; Xu, K.; Wu, X. G.; Li, Y.; Zhang, Y.; Dutta, A.; Han, C.; Vincon, I.; Rogach, A. L.; Nag, A.; Samanta, A.; Korgel, B. A.; Shih, C. J.; Gamelin, D. R.; Son, D. H.; Zeng, H.; Zhong, H.; Sun, H.; Demir, H. V.; Scheblykin, I. G.; Mora-Sero, I.; Stolarczyk, J. K.; Zhang, J. Z.; Feldmann, J.; Hofkens, J.; Luther, J. M.; Perez-Prieto, J.; Li, L.; Manna, L.; Bodnarchuk, M. I.; Kovalenko, M. V.; Roeffaers, M. B. J.; Pradhan, N.; Mohammed, O. F.; Bakr, O. M.; Yang, P.; Muller-Buschbaum, P.; Kamat, P. V.; Bao, Q.; Zhang, Q.; Krahne, R.; Galian, R. E.; Stranks, S. D.; Bals, S.; Biju, V.; Tisdale, W. A.; Yan, Y.; Hoye, R. L. Z.; Polavarapu, L. State of the Art and Prospects for Halide Perovskite Nanocrystals. ACS Nano 2021, 15, 10775– 10981,  DOI: 10.1021/acsnano.0c08903
    Google Scholar
    42
    State of the Art and Prospects for Halide Perovskite Nanocrystals
    Dey, Amrita; Ye, Junzhi; De, Apurba; Debroye, Elke; Ha, Seung Kyun; Bladt, Eva; Kshirsagar, Anuraj S.; Wang, Ziyu; Yin, Jun; Wang, Yue; Quan, Li Na; Yan, Fei; Gao, Mengyu; Li, Xiaoming; Shamsi, Javad; Debnath, Tushar; Cao, Muhan; Scheel, Manuel A.; Kumar, Sudhir; Steele, Julian A.; Gerhard, Marina; Chouhan, Lata; Xu, Ke; Wu, Xian-gang; Li, Yanxiu; Zhang, Yangning; Dutta, Anirban; Han, Chuang; Vincon, Ilka; Rogach, Andrey L.; Nag, Angshuman; Samanta, Anunay; Korgel, Brian A.; Shih, Chih-Jen; Gamelin, Daniel R.; Son, Dong Hee; Zeng, Haibo; Zhong, Haizheng; Sun, Handong; Demir, Hilmi Volkan; Scheblykin, Ivan G.; Mora-Sero, Ivan; Stolarczyk, Jacek K.; Zhang, Jin Z.; Feldmann, Jochen; Hofkens, Johan; Luther, Joseph M.; Perez-Prieto, Julia; Li, Liang; Manna, Liberato; Bodnarchuk, Maryna I.; Kovalenko, Maksym V.; Roeffaers, Maarten B. J.; Pradhan, Narayan; Mohammed, Omar F.; Bakr, Osman M.; Yang, Peidong; Mueller-Buschbaum, Peter; Kamat, Prashant V.; Bao, Qialiang; Zhang, Qiao; Krahne, Roman; Galian, Raquel E.; Stranks, Samuel D.; Bals, Sara; Biju, Vasudevanpillai; Tisdale, William A.; Yan, Yong; Hoye, Robert L. Z.; Polavarapu, Lakshminarayana
    ACS Nano (2021), 15 (7), 10775-10981CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
    A review. Metal-halide perovskites have rapidly emerged as one of the most promising materials of the 21st century, with many exciting properties and great potential for a broad range of applications, from photovoltaics to optoelectronics and photocatalysis. The ease with which metal-halide perovskites can be synthesized in the form of brightly luminescent colloidal nanocrystals, as well as their tunable and intriguing optical and electronic properties, has attracted researchers from different disciplines of science and technol. In the last few years, there has been a significant progress in the shape-controlled synthesis of perovskite nanocrystals and understanding of their properties and applications. In this comprehensive review, researchers having expertise in different fields (chem., physics, and device engineering) of metal-halide perovskite nanocrystals have joined together to provide a state of the art overview and future prospects of metal-halide perovskite nanocrystal research.
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  43. 43
    Lu, M.; Zhang, Y.; Wang, S.; Guo, J.; Yu, W. W.; Rogach, A. L. Metal Halide Perovskite Light-Emitting Devices: Promising Technology for Next-Generation Displays. Adv. Funct. Mater. 2019, 29, 1902008,  DOI: 10.1002/adfm.201902008
    Google Scholar
    There is no corresponding record for this reference.
  44. 44
    Quan, L. N.; Rand, B. P.; Friend, R. H.; Mhaisalkar, S. G.; Lee, T. W.; Sargent, E. H. Perovskites for Next-Generation Optical Sources. Chem. Rev. 2019, 119, 7444– 7477,  DOI: 10.1021/acs.chemrev.9b00107
    Google Scholar
    44
    Perovskites for Next-Generation Optical Sources
    Quan, Li Na; Rand, Barry P.; Friend, Richard H.; Mhaisalkar, Subodh Gautam; Lee, Tae-Woo; Sargent, Edward H.
    Chemical Reviews (Washington, DC, United States) (2019), 119 (12), 7444-7477CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
    Next-generation displays and lighting technologies require efficient optical sources that combine brightness, color purity, stability, substrate flexibility. Metal halide perovskites have potential use in a wide range of applications, for they possess excellent charge transport, bandgap tunability and, in the most promising recent optical source materials, intense and efficient luminescence. This review links metal halide perovskites' performance as efficient light emitters with their underlying materials electronic and photophys. attributes.
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  45. 45
    Utzat, H.; Sun, W.; Kaplan, A. E. K.; Krieg, F.; Ginterseder, M.; Spokoyny, B.; Klein, N. D.; Shulenberger, K. E.; Perkinson, C. F.; Kovalenko, M. V.; Bawendi, M. G. Coherent Single-Photon Emission From Colloidal Lead Halide Perovskite Quantum Dots. Science 2019, 363, 1068– 1072,  DOI: 10.1126/science.aau7392
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    45
    Coherent single-photon emission from colloidal lead halide perovskite quantum dots
    Utzat, Hendrik; Sun, Weiwei; Kaplan, Alexander E. K.; Krieg, Franziska; Ginterseder, Matthias; Spokoyny, Boris; Klein, Nathan D.; Shulenberger, Katherine E.; Perkinson, Collin F.; Kovalenko, Maksym V.; Bawendi, Moungi G.
    Science (Washington, DC, United States) (2019), 363 (6431), 1068-1072CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
    Chem. made colloidal semiconductor quantum dots have long been proposed as scalable and color-tunable single emitters in quantum optics, but they have typically suffered from prohibitively incoherent emission. The authors now demonstrate that individual colloidal lead halide perovskite quantum dots (PQDs) display highly efficient single-photon emission with optical coherence times as long as 80 ps, an appreciable fraction of their 210-ps radiative lifetimes. These measurements suggest that PQDs should be explored as building blocks in sources of indistinguishable single photons and entangled photon pairs. Their results present a starting point for the rational design of lead halide perovskite-based quantum emitters that have fast emission, wide spectral tunability, and scalable prodn. and that benefit from the hybrid integration with nanophotonic components that has been demonstrated for colloidal materials.
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  46. 46
    Raino, G.; Nedelcu, G.; Protesescu, L.; Bodnarchuk, M. I.; Kovalenko, M. V.; Mahrt, R. F.; Stoferle, T. Single Cesium Lead Halide Perovskite Nanocrystals at Low Temperature: Fast Single-Photon Emission, Reduced Blinking, and Exciton Fine Structure. ACS Nano 2016, 10, 2485– 2490,  DOI: 10.1021/acsnano.5b07328
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    46
    Single Cesium Lead Halide Perovskite Nanocrystals at Low Temperature: Fast Single-Photon Emission, Reduced Blinking, and Exciton Fine Structure
    Raino, Gabriele; Nedelcu, Georgian; Protesescu, Loredana; Bodnarchuk, Maryna I.; Kovalenko, Maksym V.; Mahrt, Rainer F.; Stoferle, Thilo
    ACS Nano (2016), 10 (2), 2485-2490CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
    At low temp. single colloidal CsPbX3 (X = Cl/Br) nanocrystals exhibit stable, narrow-band emission with suppressed blinking and small spectral diffusion. Photon antibunching demonstrates unambiguously nonclassical single-photon emission with radiative decay ∼250 ps, representing a significant acceleration compared to other common quantum emitters. High-resoln. spectroscopy provides insight into the complex nature of the emission process such as the fine structure and charged exciton dynamics.
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  47. 47
    Almeida, G.; Goldoni, L.; Akkerman, Q.; Dang, Z.; Khan, A. H.; Marras, S.; Moreels, I.; Manna, L. Role of Acid-Base Equilibria in the Size, Shape, and Phase Control of Cesium Lead Bromide Nanocrystals. ACS Nano 2018, 12, 1704– 1711,  DOI: 10.1021/acsnano.7b08357
    Google Scholar
    47
    Role of Acid-Base Equilibria in the Size, Shape, and Phase Control of Cesium Lead Bromide Nanocrystals
    Almeida, Guilherme; Goldoni, Luca; Akkerman, Quinten; Dang, Zhiya; Khan, Ali Hossain; Marras, Sergio; Moreels, Iwan; Manna, Liberato
    ACS Nano (2018), 12 (2), 1704-1711CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
    A binary ligand system composed of aliph. carboxylic acids and primary amines of various chain lengths is commonly employed in diverse synthesis methods for CsPbBr3 nanocrystals (NCs). The authors have carried out a systematic study examg. how the concn. of ligands (oleylamine and oleic acid) and the resulting acidity (or basicity) affects the hot-injection synthesis of CsPbBr3 NCs. The authors devise a general synthesis scheme for cesium lead bromide NCs which allows control over size, size distribution, shape, and phase (CsPbBr3 or Cs4PbBr6) by combining key insights on the acid-base interactions that rule this ligand system. Also, the authors' findings shed light upon the soly. of PbBr2 in this binary ligand system, and plausible mechanisms are suggested to understand the ligand-mediated phase control and structural stability of CsPbBr3 NCs.
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  48. 48
    Hudait, B.; Dutta, S. K.; Patra, A.; Nasipuri, D.; Pradhan, N. Facets Directed Connecting Perovskite Nanocrystals. J. Am. Chem. Soc. 2020, 142, 7207– 7217,  DOI: 10.1021/jacs.0c02168
    Google Scholar
    48
    Facets Directed Connecting Perovskite Nanocrystals
    Hudait, Biswajit; Dutta, Sumit Kumar; Patra, Avijit; Nasipuri, Diptam; Pradhan, Narayan
    Journal of the American Chemical Society (2020), 142 (15), 7207-7217CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
    Connecting nanocrystals with removal of interface ligand barriers is one of the key steps for efficient carrier transportation in optoelectronic device fabrication. Typically, ion migration for crystal deformation or connection with other nanocrystals needs a solvent as medium. However, on the contrary, this has been obsd. for CsPbBr3 perovskite nanocrystals in film where nanocrystals were swollen to get wider and fused with adjacent nanocrystals in self-assembly on film during solvent evapn. Depending on precursor compn. and exposed facets, again these connections could be programmed for tuning their connecting directions leading to different shapes. Aging further on solid substrate, these were also turned to continuous film of nanostructures eliminating all interparticle gaps on the film. This transformation could be ceased at any point of time, simply by heating or adding sufficient ligands. Anal. suggested that these unique and controlled connections were only obsd. with polyhedron shaped nanostructures with certain compns. and not with traditionally cubes. Details of this solid-surface transformation during solvent evapn. were analyzed, and an interparticle material transfer type mechanism was proposed. As these observations were not seen in chalcogenide and oxide nanocrystals and exclusively obsd. in perovskite nanocrystals, this would add new fundamentals to the insights of crystal growths of nanocrystals and would also help in obtaining films of connecting nanocrystals.
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  49. 49
    Bera, S.; Behera, R. K.; Pradhan, N. alpha-Halo Ketone for Polyhedral Perovskite Nanocrystals: Evolutions, Shape Conversions, Ligand Chemistry, and Self-Assembly. J. Am. Chem. Soc. 2020, 142, 20865– 20874,  DOI: 10.1021/jacs.0c10688
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    49
    α-Halo Ketone for Polyhedral Perovskite Nanocrystals: Evolutions, Shape Conversions, Ligand Chemistry, and Self-Assembly
    Bera, Suman; Behera, Rakesh Kumar; Pradhan, Narayan
    Journal of the American Chemical Society (2020), 142 (49), 20865-20874CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
    Bright lead halide perovskite nanocrystals, which have been extensively studied in the past 5 years, are mostly confined to a six faceted hexahedron (cube/platelet) shape. With variations of ligand, precursor, reaction temp., and surface modification, their brightness has been enhanced and phase became stable, but ultimate nanocrystals still retained the hexahedron cube or platelet shape in most of the hot injection reactions. In contrast, by exploration of α-halo ketone in amine as a halide precursor, different shaped nanocrystals without compromising the photoluminescence quantum yield (PLQY) are reported. Confining to orthorhombic CsPbBr3, the obtained nanocrystals are stabilized by 12 facets ({200}, {020}, {112}) and led to 12 faceted rhombic dodecahedrons. These facets are absolutely different from six ({110}, {002}) equiv. facets of widely reported orthorhombic cube shaped CsPbBr3 nanocrystals. These also retained the colloidal and phase stability, as well as showed near unity PLQY. With further annealing, these are transformed to 26 faceted rhombicuboctahedrons by dissolving all their vertices. Importantly, these 12 faceted nanocrystals showed wide area self-assembly in most of the reactions. It has also been concluded that primary ammonium ions led to six faceted nanocrystals, but tertiary ammonium ions obtained in this case stabilized different group of facets. While perovskite nanocrystals were broadly confined to only nanocubes, these new nanocrystals with intense emission would certainly provide a new avenue for continuing their further research.
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  50. 50
    Kovalenko, M. V.; Bodnarchuk, M. I. Lead Halide Perovskite Nanocrystals: From Discovery to Self-Assembly and Applications. Chimia 2017, 71, 461– 470,  DOI: 10.2533/chimia.2017.461
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    50
    Lead halide perovskite nanocrystals: from discovery to self-assembly and applications
    Kovalenko, Maksym V.; Bodnarchuk, Maryna I.
    Chimia (2017), 71 (7-8), 461-470CODEN: CHIMAD ISSN:. (Swiss Chemical Society)
    A review. Lead halide perovskites (LHPs) of the general formula APbX3 (A=Cs+, CH3NH3+, or CH(NH2)2+; X=Cl, Br, or I) have recently emerged as a unique class of low-cost, versatile semiconductors of high optoelectronic quality. These materials offer exceptionally facile soln.-based engineerability in the form of bulk single crystals, thin films, or supported and unsupported nanostructures. The lattermost form, esp. as colloidal nanocrystals (NCs), holds great promise as a versatile photonic source, operated via bright photoluminescence (PL) in displays or lighting (energy down-conversion of blue light into green and red), or via electroluminescence in light-emitting diodes. In this article we discuss the recent history of the development of highly-luminescent NCs of LHPs, the current state-of-the-art of this class of materials, and the future prospects of this highly active research field. We also report the demonstration of long-range ordered, self-organized superlattice structures obtained from cubeshaped colloidal CsPbBr3 NCs using drying-mediated self-assembly.
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  51. 51
    Nagaoka, Y.; Hills-Kimball, K.; Tan, R.; Li, R.; Wang, Z.; Chen, O. Nanocube Superlattices of Cesium Lead Bromide Perovskites and Pressure-Induced Phase Transformations at Atomic and Mesoscale Levels. Adv. Mater. 2017, 29, 1606666,  DOI: 10.1002/adma.201606666
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  52. 52
    van der Burgt, J. S.; Geuchies, J. J.; van der Meer, B.; Vanrompay, H.; Zanaga, D.; Zhang, Y.; Albrecht, W.; Petukhov, A. V.; Filion, L.; Bals, S.; Swart, I.; Vanmaekelbergh, D. Cuboidal Supraparticles Self-Assembled from Cubic CsPbBr3 Perovskite Nanocrystals. J. Phys. Chem. C 2018, 122, 15706– 15712,  DOI: 10.1021/acs.jpcc.8b02699
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    52
    Cuboidal Supraparticles Self-Assembled from Cubic CsPbBr3 Perovskite Nanocrystals
    van der Burgt, Julia S.; Geuchies, Jaco J.; van der Meer, Berend; Vanrompay, Hans; Zanaga, Daniele; Zhang, Yang; Albrecht, Wiebke; Petukhov, Andrei V.; Filion, Laura; Bals, Sara; Swart, Ingmar; Vanmaekelbergh, Daniel
    Journal of Physical Chemistry C (2018), 122 (27), 15706-15712CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)
    Colloidal CsPbBr3 nanocrystals (NCs) have emerged as promising candidates for various opto-electronic applications, such as light-emitting diodes, photodetectors, and solar cells. Here, we report on the self-assembly of cubic NCs from an org. suspension into ordered cuboidal supraparticles (SPs) and their structural and optical properties. Upon increasing the NC concn. or by addn. of a nonsolvent, the formation of the SPs occurs homogeneously in the suspension, as monitored by in situ X-ray scattering measurements. The three-dimensional structure of the SPs was resolved through high-angle annular dark-field scanning transmission electron microscopy and electron tomog. The NCs are atomically aligned but not connected. We characterize NC vacancies on superlattice positions both in the bulk and on the surface of the SPs. The occurrence of localized at.-type NC vacancies-instead of delocalized ones-indicates that NC-NC attractions are important in the assembly, as we verify with Monte Carlo simulations. Even when assembled in SPs, the NCs show bright emission, with a red shift of about 30 meV compared to NCs in suspension.
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  53. 53
    Rainò, G.; Becker, M. A.; Bodnarchuk, M. I.; Mahrt, R. F.; Kovalenko, M. V.; Stöferle, T. Superfluorescence From Lead Halide Perovskite Quantum Dot Superlattices. Nature 2018, 563, 671– 675,  DOI: 10.1038/s41586-018-0683-0
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    53
    Superfluorescence from lead halide perovskite quantum dot superlattices
    Raino, Gabriele; Becker, Michael A.; Bodnarchuk, Maryna I.; Mahrt, Rainer F.; Kovalenko, Maksym V.; Stoferle, Thilo
    Nature (London, United Kingdom) (2018), 563 (7733), 671-675CODEN: NATUAS; ISSN:0028-0836. (Nature Research)
    An ensemble of emitters can behave very differently from its individual constituents when they interact coherently via a common light field. After excitation of such an ensemble, collective coupling can give rise to a many-body quantum phenomenon that results in short, intense bursts of light-so-called superfluorescence1. Because this phenomenon requires a fine balance of interactions between the emitters and their decoupling from the environment, together with close identity of the individual emitters, superfluorescence has thus far been obsd. only in a limited no. of systems, such as certain at. and mol. gases and a few solid-state systems2-7. The generation of superfluorescent light in colloidal nanocrystals (which are bright photonic sources practically suited for optoelectronics8,9) has been precluded by inhomogeneous emission broadening, low oscillator strength, and fast exciton dephasing. Here we show that cesium lead halide (CsPbX3, X = Cl, Br) perovskite nanocrystals10-13 that are self-organized into highly ordered three-dimensional superlattices exhibit key signatures of superfluorescence. These are dynamically red-shifted emission with more than 20-fold accelerated radiative decay, extension of the first-order coherence time by more than a factor of four, photon bunching, and delayed emission pulses with Burnham-Chiao ringing behavior14 at high excitation d. These mesoscopically extended coherent states could be used to boost the performance of optoelectronic devices15 and enable entangled multi-photon quantum light sources16,17.
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  54. 54
    Baranov, D.; Toso, S.; Imran, M.; Manna, L. Investigation into the Photoluminescence Red Shift in Cesium Lead Bromide Nanocrystal Superlattices. J. Phys. Chem. Lett. 2019, 10, 655– 660,  DOI: 10.1021/acs.jpclett.9b00178
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    54
    Investigation into the Photoluminescence Red Shift in Cesium Lead Bromide Nanocrystal Superlattices
    Baranov, Dmitry; Toso, Stefano; Imran, Muhammad; Manna, Liberato
    Journal of Physical Chemistry Letters (2019), 10 (3), 655-660CODEN: JPCLCD; ISSN:1948-7185. (American Chemical Society)
    The formation of cesium lead bromide (CsPbBr3) nanocrystal superlattices (NC SLs) is accompanied by a red shift in the NC photoluminescence (PL). The values of the PL red shift reported in the literature range from none to ∼100 meV without unifying explanation of the differences. Using a combination of confocal PL microcopy and steady-state optical spectroscopies we found that an overall PL red shift of ∼96 meV measured from a macroscopic sample of CsPbBr3 NC SLs has several contributions: ∼ 10-15 meV from a red shift in isolated and clean SLs, ∼ 30 meV from SLs with impurities of bulklike CsPbBr3 crystals on their surface, and up to 50 meV or more of the red shift coming from a photon propagation effect, specifically self-absorption. In addn., a self-assembly technique for growing micron-sized NC SLs on the surface of perfluorodecalin, an inert perfluorinated liq. and an antisolvent for NCs, is described.
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  55. 55
    Tong, Y.; Yao, E. P.; Manzi, A.; Bladt, E.; Wang, K.; Doblinger, M.; Bals, S.; Muller-Buschbaum, P.; Urban, A. S.; Polavarapu, L.; Feldmann, J. Spontaneous Self-Assembly of Perovskite Nanocrystals into Electronically Coupled Supercrystals: Toward Filling the Green Gap. Adv. Mater. 2018, 30, 1801117  DOI: 10.1002/adma.201801117
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    There is no corresponding record for this reference.
  56. 56
    Imran, M.; Ijaz, P.; Baranov, D.; Goldoni, L.; Petralanda, U.; Akkerman, Q.; Abdelhady, A. L.; Prato, M.; Bianchini, P.; Infante, I.; Manna, L. Shape-Pure, Nearly Monodispersed CsPbBr3 Nanocubes Prepared Using Secondary Aliphatic Amines. Nano Lett. 2018, 18, 7822– 7831,  DOI: 10.1021/acs.nanolett.8b03598
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    56
    Shape-Pure, Nearly Monodispersed CsPbBr3 Nanocubes Prepared Using Secondary Aliphatic Amines
    Imran, Muhammad; Ijaz, Palvasha; Baranov, Dmitry; Goldoni, Luca; Petralanda, Urko; Akkerman, Quinten; Abdelhady, Ahmed L.; Prato, Mirko; Bianchini, Paolo; Infante, Ivan; Manna, Liberato
    Nano Letters (2018), 18 (12), 7822-7831CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
    Fully inorg. Cs lead halide perovskite (CsPbX3) nanocrystals (NCs) were extensively studied due to their excellent optical properties, esp. their high photoluminescence quantum yield (PLQY) and the ease with which the PL can be tuned across the visible spectrum. So far, most strategies for synthesizing CsPbX3 NCs are highly sensitive to the processing conditions and ligand combinations. For example, in the synthesis of nanocubes of different sizes, it is not uncommon to have samples that contain various other shapes, such as nanoplatelets and nanosheets. Here, the authors report a new colloidal synthesis method for prepg. shape-pure and nearly monodispersed CsPbBr3 nanocubes using secondary amines. Regardless of the length of the alkyl chains, the oleic acid concn., and the reaction temp., only cube-shaped NCs were obtained. The shape purity and narrow size distribution of the nanocubes are evident from their sharp excitonic features and their ease of self-assembly in superlattices, reaching lateral dimensions of up to 50 μm. The authors attribute this excellent shape and phase purity to the inability of secondary amines to find the right steric conditions at the surface of the NCs, which consequently limits the formation of low-dimensional structures. Also, no contamination from other phases was obsd., not even from Cs4PbBr6, presumably due to the poor ability of secondary aliph. amines to coordinate to PbBr2 and, hence, to provide a reaction environment that is depleted in Pb.
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  57. 57
    Toso, S.; Baranov, D.; Giannini, C.; Marras, S.; Manna, L. Wide-Angle X-ray Diffraction Evidence of Structural Coherence in CsPbBr3 Nanocrystal Superlattices. ACS Mater. Lett. 2019, 1, 272– 276,  DOI: 10.1021/acsmaterialslett.9b00217
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    57
    Wide-Angle X-ray Diffraction Evidence of Structural Coherence in CsPbBr3 Nanocrystal Superlattices
    Toso, Stefano; Baranov, Dmitry; Giannini, Cinzia; Marras, Sergio; Manna, Liberato
    ACS Materials Letters (2019), 1 (2), 272-276CODEN: AMLCEF; ISSN:2639-4979. (American Chemical Society)
    Films made of colloidal CsPbBr3 nanocrystals packed in isolated or densely-packed superlattices display a remarkably high degree of structural coherence. The structural coherence is revealed by the presence of satellite peaks accompanying Bragg reflections in wide-angle X-ray diffraction expts. in parallel-beam reflection geometry. The satellite peaks, also called "superlattice reflections", arise from the interference of X-rays diffracted by the at. planes of the orthorhombic perovskite lattice. The interference is due to the precise spatial periodicity of the nanocrystals sepd. by org. ligands in the superlattice. The presence of satellite peaks is a fingerprint of the high crystallinity and long-range order of nanocrystals, comparable to those of multilayer superlattices prepd. by phys. methods. The angular sepn. between satellite peaks is highly sensitive to changes in the superlattice periodicity. These characteristics of the satellite peaks are exploited to track the superlattice compression under vacuum, as well as to observe the superlattice growth in situ from colloidal solns. by slow solvent evapn.
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  58. 58
    Cherniukh, I.; Rainò, G.; Stöferle, T.; Burian, M.; Travesset, A.; Naumenko, D.; Amenitsch, H.; Erni, R.; Mahrt, R. F.; Bodnarchuk, M. I.; Kovalenko, M. V. Perovskite-Type Superlattices from Lead Halide Perovskite Nanocubes. Nature 2021, 593, 535– 542,  DOI: 10.1038/s41586-021-03492-5
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    58
    Perovskite-type superlattices from lead halide perovskite nanocubes
    Cherniukh, Ihor; Raino, Gabriele; Stoferle, Thilo; Burian, Max; Travesset, Alex; Naumenko, Denys; Amenitsch, Heinz; Erni, Rolf; Mahrt, Rainer F.; Bodnarchuk, Maryna I.; Kovalenko, Maksym V.
    Nature (London, United Kingdom) (2021), 593 (7860), 535-542CODEN: NATUAS; ISSN:0028-0836. (Nature Portfolio)
    Perovskite-type (ABO3) binary and ternary nanocrystal superlattices, created via the shape-directed co-assembly of steric-stabilized, highly luminescent cubic CsPbBr3 nanocrystals (which occupy the B and/or O lattice sites), spherical Fe3O4 or NaGdF4 nanocrystals (A sites) and truncated-cuboid PbS nanocrystals (B sites), are presented. These ABO3 superlattices, as well as the binary NaCl and AlB2 superlattice structures that the authors demonstrate, exhibit a high degree of orientational ordering of the CsPbBr3 nanocubes. They also exhibit superfluorescence - a collective emission that results in a burst of photons with ultrafast radiative decay (22 ps) that could be tailored for use in ultrabright (quantum) light sources. The work paves the way for further exploration of complex, ordered and functionally useful perovskite mesostructures.
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  59. 59
    Cherniukh, I.; Raino, G.; Sekh, T. V.; Zhu, C.; Shynkarenko, Y.; John, R. A.; Kobiyama, E.; Mahrt, R. F.; Stoferle, T.; Erni, R.; Kovalenko, M. V.; Bodnarchuk, M. I. Shape-Directed Co-Assembly of Lead Halide Perovskite Nanocubes with Dielectric Nanodisks into Binary Nanocrystal Superlattices. ACS Nano 2021, 15, 16488– 16500,  DOI: 10.1021/acsnano.1c06047
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    59
    Shape-Directed Co-Assembly of Lead Halide Perovskite Nanocubes with Dielectric Nanodisks into Binary Nanocrystal Superlattices
    Cherniukh, Ihor; Raino, Gabriele; Sekh, Taras V.; Zhu, Chenglian; Shynkarenko, Yevhen; John, Rohit Abraham; Kobiyama, Etsuki; Mahrt, Rainer F.; Stoferle, Thilo; Erni, Rolf; Kovalenko, Maksym V.; Bodnarchuk, Maryna I.
    ACS Nano (2021), 15 (10), 16488-16500CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
    Self-assembly of colloidal nanocrystals (NCs) holds great promise in the multiscale engineering of solid-state materials, whereby atomically engineered NC building blocks are arranged into long-range ordered structures-superlattices (SLs)-with synergistic phys. and chem. properties. Thus far, the reports have by far focused on single-component and binary systems of spherical NCs, yielding SLs isostructural with the known at. lattices. Far greater structural space, beyond the realm of known lattices, is anticipated from combining NCs of various shapes. Here, we report on the co-assembly of steric-stabilized CsPbBr3 nanocubes (5.3 nm) with disk-shaped LaF3 NCs (9.2-28.4 nm in diam., 1.6 nm in thickness) into binary SLs, yielding six columnar structures with AB, AB2, AB4, and AB6 stoichiometry, not obsd. before and in our ref. expts. with NC systems comprising spheres and disks. This striking effect of the cubic shape is rationalized herein using packing-d. calcns. Furthermore, in the systems with comparable dimensions of nanocubes (8.6 nm) and nanodisks (6.5 nm, 9.0 nm, 12.5 nm), other, noncolumnar structures are obsd., such as ReO3-type SL, featuring intimate intermixing and face-to-face alignment of disks and cubes, face-centered cubic or simple cubic sublattice of nanocubes, and two or three disks per one lattice site. Lamellar and ReO3-type SLs, employing large 8.6 nm CsPbBr3 NCs, exhibit characteristic features of the collective ultrafast light emission-superfluorescence-originating from the coherent coupling of emission dipoles in the excited state.
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  60. 60
    Bertolotti, F.; Nedelcu, G.; Vivani, A.; Cervellino, A.; Masciocchi, N.; Guagliardi, A.; Kovalenko, M. V. Crystal Structure, Morphology, and Surface Termination of Cyan-Emissive, Six-Monolayers-Thick CsPbBr3 Nanoplatelets from X-Ray Total Scattering. ACS Nano 2019, 13, 14294– 14307,  DOI: 10.1021/acsnano.9b07626
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    60
    Crystal Structure, Morphology, and Surface Termination of Cyan-Emissive, Six-Monolayers-Thick CsPbBr3 Nanoplatelets from X-ray Total Scattering
    Bertolotti, Federica; Nedelcu, Georgian; Vivani, Anna; Cervellino, Antonio; Masciocchi, Norberto; Guagliardi, Antonietta; Kovalenko, Maksym V.
    ACS Nano (2019), 13 (12), 14294-14307CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
    Highly anisotropic colloidal CsPbBr3 nanoplatelets (NPLs) represent an appealing class of colloidal quantum wells with enhanced light emissivity. Strong quantum confinement imposed by the small platelet thickness and at. flatness gives rise to enhanced oscillator strength, higher exciton binding energy, and narrow emission linewidth. While discrete thicknesses manifest themselves in discrete bandgap energies, fine-tuning of the emission energy can be achieved by compositional modulations. Here we address one of the most debated aspects of perovskite nanoplatelets: their crystal structure. Starting with the direct imaging by high-resoln. electron microscopy (providing a clue on the pseudocubic faceting of the NPLs), we focus the study on X-ray total scattering techniques, based on the Debye scattering equation (DSE) approach, to obtain better atomistic insight. The nanoplatelets are six-monolayers thick and exhibit an orthorhombic structure. A thorough structure-morphol. characterization unveils a specific orientation of the axial and equatorial bromides of the PbBr6 octahedra vs. the NPLs thickness; we found that {010} and {101} planes of the orthorhombic CsPbBr3 lattice (Pnma space group) correspond to the six facets of the NPL, with basal planes being of {101} type. The NPLs undergo a lattice relaxation in comparison to cuboidal CsPbBr3 NCs; the major deformation is obsd. in the axial direction, which suggests a structural origin of the higher compliance along the b axis. The DSE-based anal. also supports a CsBr surface termination model, with half Cs sites and a half (or slightly more) Br sites vacant.
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  61. 61
    Dong, Y.; Qiao, T.; Kim, D.; Parobek, D.; Rossi, D.; Son, D. H. Precise Control of Quantum Confinement in Cesium Lead Halide Perovskite Quantum Dots via Thermodynamic Equilibrium. Nano Lett. 2018, 18, 3716– 3722,  DOI: 10.1021/acs.nanolett.8b00861
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    61
    Precise Control of Quantum Confinement in Cesium Lead Halide Perovskite Quantum Dots via Thermodynamic Equilibrium
    Dong, Yitong; Qiao, Tian; Kim, Doyun; Parobek, David; Rossi, Daniel; Son, Dong Hee
    Nano Letters (2018), 18 (6), 3716-3722CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
    Cs lead halide (CsPbX3) nanocrystals have emerged as a new family of materials that can outperform the existing semiconductor nanocrystals due to their superb optical and charge-transport properties. However, the lack of a robust method for producing quantum dots with controlled size and high ensemble uniformity was 1 of the major obstacles in exploring the useful properties of excitons in zero-dimensional nanostructures of CsPbX3. Here, the authors report a new synthesis approach that enables the precise control of the size based on the equil. rather than kinetics, producing CsPbX3 quantum dots nearly free of heterogeneous broadening in their exciton luminescence. The high level of size control and ensemble uniformity achieved here will open the door to harnessing the benefits of excitons in CsPbX3 quantum dots for photonic and energy-harvesting applications.
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  62. 62
    Bodnarchuk, M. I.; Boehme, S. C.; Ten Brinck, S.; Bernasconi, C.; Shynkarenko, Y.; Krieg, F.; Widmer, R.; Aeschlimann, B.; Gunther, D.; Kovalenko, M. V.; Infante, I. Rationalizing and Controlling the Surface Structure and Electronic Passivation of Cesium Lead Halide Nanocrystals. ACS Energy Lett. 2019, 4, 63– 74,  DOI: 10.1021/acsenergylett.8b01669
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    62
    Rationalizing and Controlling the Surface Structure and Electronic Passivation of Cesium Lead Halide Nanocrystals
    Bodnarchuk, Maryna I.; Boehme, Simon C.; ten Brinck, Stephanie; Bernasconi, Caterina; Shynkarenko, Yevhen; Krieg, Franziska; Widmer, Roland; Aeschlimann, Beat; Gunther, Detlef; Kovalenko, Maksym V.; Infante, Ivan
    ACS Energy Letters (2019), 4 (1), 63-74CODEN: AELCCP; ISSN:2380-8195. (American Chemical Society)
    Colloidal lead halide perovskite nanocrystals (NCs) have recently emerged as versatile photonic sources. Their processing and luminescent properties are challenged by the lability of their surfaces, i.e., the interface of the NC core and the ligand shell. On the example of CsPbBr3 NCs, we model the nanocrystal surface structure and its effect on the emergence of trap states using d. functional theory. We rationalize the typical observation of a degraded luminescence upon aging or the luminescence recovery upon postsynthesis surface treatments. The conclusions are corroborated by the elemental anal. We then propose a strategy for healing the surface trap states and for improving the colloidal stability by the combined treatment with didodecyldimethylammonium bromide and lead bromide and validate this approach exptl. This simple procedure results in robust colloids, which are highly pure and exhibit high photoluminescence quantum yields of up to 95-98%, retained even after three to four rounds of washing.
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  63. 63
    Park, J.; An, K.; Hwang, Y.; Park, J. G.; Noh, H. J.; Kim, J. Y.; Park, J. H.; Hwang, N. M.; Hyeon, T. Ultra-Large-Scale Syntheses of Monodisperse Nanocrystals. Nat. Mater. 2004, 3, 891– 895,  DOI: 10.1038/nmat1251
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    63
    Ultra-large-scale syntheses of monodisperse nanocrystals
    Park, Jongnam; An, Kwangjin; Hwang, Yosun; Park, Je-Geun; Noh, Han-Jin; Kim, Jae-Young; Park, Jae-Hoon; Hwang, Nong-Moon; Hyeon, Taeghwan
    Nature Materials (2004), 3 (12), 891-895CODEN: NMAACR; ISSN:1476-1122. (Nature Publishing Group)
    The development of nanocrystals has been intensively pursued, not only for their fundamental scientific interest, but also for many technol. applications. The synthesis of monodisperse nanocrystals (size variation <5%) is of key importance, because the properties of these nanocrystals depend strongly on their dimensions. For example, the color sharpness of semiconductor nanocrystal-based optical devices is strongly dependent on the uniformity of the nanocrystals, and monodisperse magnetic nanocrystals are crit. for the next-generation multiterabit magnetic storage media. For these monodisperse nanocrystals to be used, an economical mass prodn. method needs to be developed. Unfortunately, however, in most syntheses reported so far, only subgram quantities of monodisperse nanocrystals were produced. Uniform-sized nanocrystals of CdSe and Au have been produced using colloidal chem. synthetic procedures. In addn., monodisperse magnetic nanocrystals such as Fe, Co, γ-Fe2O3, and Fe3O4 have been synthesized by using various synthetic methods. Here, we report on the ultralarge-scale synthesis of monodisperse nanocrystals using inexpensive and nontoxic metal salts as reactants. We were able to synthesize as much as 40 g of monodisperse nanocrystals in a single reaction, without a size sorting process. Moreover, the particle size could be controlled simply by varying the exptl. conditions. The current synthetic procedure is very general and nanocrystals of many transition metal oxides were successfully synthesized using a very similar procedure.
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  64. 64
    Travesset, A. Topological Structure Prediction in Binary Nanoparticle Superlattices. Soft Matter 2017, 13, 147– 157,  DOI: 10.1039/C6SM00713A
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    64
    Topological structure prediction in binary nanoparticle superlattices
    Travesset, A.
    Soft Matter (2017), 13 (1), 147-157CODEN: SMOABF; ISSN:1744-683X. (Royal Society of Chemistry)
    Systems of spherical nanoparticles with capping ligands have been shown to self-assemble into beautiful superlattices of fascinating structure and complexity. In this paper, I show that the spherical geometry of the nanoparticle imposes constraints on the nature of the topol. defects assocd. with the capping ligand and that such topol. defects control the structure and stability of the superlattices that can be assembled. All these considerations form the basis for the orbifold topol. model (OTM) described in this paper. The model quant. predicts the structure of super-lattices where capping ligands are hydrocarbon chains in excellent agreement with exptl. results, explains the appearance of low packing fraction lattices as equil., why certain similar structures are more stable (bccAB6vs. CaB6, AuCu vs. CsCl, etc.) and many other exptl. observations.
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  65. 65
    Boles, M. A.; Talapin, D. V. Binary Assembly of PbS and Au Nanocrystals: Patchy PbS Surface Ligand Coverage Stabilizes the CuAu Superlattice. ACS Nano 2019, 13, 5375– 5384,  DOI: 10.1021/acsnano.9b00006
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    65
    Binary Assembly of PbS and Au Nanocrystals: Patchy PbS Surface Ligand Coverage Stabilizes the CuAu Superlattice
    Boles, Michael A.; Talapin, Dmitri V.
    ACS Nano (2019), 13 (5), 5375-5384CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
    Self-assembly of two sizes of nearly spherical colloidal nanocrystals (NCs) capped with hydrocarbon surface ligands has been shown to produce more than 20 distinct phases of binary nanocrystal superlattices (BNSLs). Such structural diversity, in striking contrast to binary systems of micron-sized colloidal beads, cannot be rationalized by models assuming entropy-driven crystn. of simple spheres. In this work, we show that the PbS ligand binding equil. controls the relative stability of two closely related BNSL structures featuring alternating layers of PbS and Au NCs. At an intermediate size ratio, as-prepd. PbS NCs assemble with Au NCs into CuAu BNSLs featuring orientational coherence of PbS NCs across the lattice. Measurement of interparticle sepns. within CuAu and modeling of the structure reveal that PbS inorg. cores are nearly in contact through (100) NC surfaces in the square tiling of the CuAu basal plane. On the other hand, AlB2 BNSLs with PbS NCs packed in random orientations were found to be the dominant self-assembly product when the same binary NC soln. was evapd. in the presence of added oleic acid (OAH). Soln. NMR titrn. expts. confirmed that added OAH binds to PbS NCs, implicating ligand surface coverage as an important factor influencing the relative stability of CuAu and AlB2 BNSLs at the exptl. size ratio. From these results, we conclude that as-prepd. PbS NCs feature sparsely covered (100) surfaces and thus effectively flat patches along NC x-, y-, and z-directions. Such anisotropic PbS-PbS interactions can be efficiently screened by restoring effectively spherical NC shape via addn. of OAH to the binary assembly soln. Our findings underscore the important contribution of NC surfaces to superlattice phase stability and offer a strategy for targeted BNSL assembly.
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  66. 66
    Zhuang, J.; Wu, H.; Yang, Y.; Cao, Y. C. Supercrystalline Colloidal Particles from Artificial Atoms. J. Am. Chem. Soc. 2007, 129, 14166– 14167,  DOI: 10.1021/ja076494i
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    66
    Supercrystalline colloidal particles from artificial atoms
    Zhuang, Jiaqi; Wu, Huimeng; Yang, Yongan; Cao, Y. Charles
    Journal of the American Chemical Society (2007), 129 (46), 14166-14167CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
    In this paper, we report an approach for using solvophobic interactions to synthesize well-defined colloidal superparticles from nonpolar-solvent-dispersible Fe3O4 nanoparticle artificial atoms. These colloidal superparticles possess a "single-supercrystal" structure, of which Fe3O4 artificial atoms occupy the lattice points of a face-centered cubic superlattice. In addn., these superparticles exhibit superlattice fringes under a low-resoln. TEM, providing an interesting analog to the lattice fringes of colloidal nanocrystals under a high-resoln. TEM. Moreover, these superparticles can be further assembled into close-packed solid structures, demonstrating their role as a new type of building block in nanoscience.
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  67. 67
    Zhuang, J.; Wu, H.; Yang, Y.; Cao, Y. C. Controlling Colloidal Superparticle Growth through Solvophobic Interactions. Angew. Chem., Int. Ed. 2008, 47, 2208– 2212,  DOI: 10.1002/anie.200705049
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    67
    Controlling colloidal superparticle growth through solvophobic interactions
    Zhuang, Jiaqi; Wu, Huimeng; Yang, Yongan; Cao, Y. Charles
    Angewandte Chemie, International Edition (2008), 47 (12), 2208-2212CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
    A supramol. chem. approach is used to make supercryst. spherical colloidal superparticles from nanoparticles. Detailed mechanistic studies show that the formation of the SPs is a two-step process. The major driving force for superparticle formation is the solvophobic interaction between nanoparticle building blocks and the growth soln.; fine-tuning the interaction led to a size-controlled synthesis.
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  68. 68
    Yang, Y.; Wang, B.; Shen, X.; Yao, L.; Wang, L.; Chen, X.; Xie, S.; Li, T.; Hu, J.; Yang, D.; Dong, A. Scalable Assembly of Crystalline Binary Nanocrystal Superparticles and Their Enhanced Magnetic and Electrochemical Properties. J. Am. Chem. Soc. 2018, 140, 15038– 15047,  DOI: 10.1021/jacs.8b09779
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    68
    Scalable Assembly of Crystalline Binary Nanocrystal Superparticles and Their Enhanced Magnetic and Electrochemical Properties
    Yang, Yuchi; Wang, Biwei; Shen, Xiudi; Yao, Luyin; Wang, Lei; Chen, Xiao; Xie, Songhai; Li, Tongtao; Hu, Jianhua; Yang, Dong; Dong, Angang
    Journal of the American Chemical Society (2018), 140 (44), 15038-15047CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
    Self-assembled binary nanocrystal superlattices (BNSLs) represent an important class of solid-state materials with potentially designed properties. In pursuit of widening the range of applications for binary superlattice materials, it is desirable to develop scalable assembly methods that enable high-quality BNSLs with tailored compns., structures, and morphologies. We report the gram-scale assembly of cryst. binary nanocrystal superparticles with high phase purity through an emulsion-based process. The structure of the resulting BNSL colloids can be tuned in a wide range (AB13, AlB2, MgZn2, NaCl, and CaCu5) by varying the size and(or) no. ratios of the 2 nanocrystal components. Access to large-scale, phase-pure BNSL colloids offers vast opportunities for investigating their physiochem. properties, as exemplified by AB13-type CoFe2O4-Fe3O4 binary superparticles. CoFe2O4-Fe3O4 binary superparticles not only display enhanced magnetic coupling but also exhibit superior lithium-storage properties. The nonclosed-packed NC packing arrangements of AB13-type binary superparticles are found to play a key role in facilitating lithiation/delithiation kinetics and maintaining structural integrity during repeated cycling. Our work establishes the scalable assembly of high-quality BNSL colloids, which is beneficial for accelerating the exploration of multicomponent nanocrystal superlattices toward various applications.
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  69. 69
    Kister, T.; Mravlak, M.; Schilling, T.; Kraus, T. Pressure-Controlled Formation of Crystalline, Janus, and Core-Shell Supraparticles. Nanoscale 2016, 8, 13377– 13384,  DOI: 10.1039/C6NR01940D
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    69
    Pressure-controlled formation of crystalline, Janus, and core-shell supraparticles
    Kister, Thomas; Mravlak, Marko; Schilling, Tanja; Kraus, Tobias
    Nanoscale (2016), 8 (27), 13377-13384CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)
    Binary mixts. of nanoparticles self-assemble in the confinement of evapg. oil droplets and form regular supraparticles. We demonstrate that moderate pressure differences on the order of 100 kPa change the particles' self-assembly behavior. Cryst. superlattices, Janus particles, and core-shell particle arrangements form in the same dispersions when changing the working pressure or the surfactant that sets the Laplace pressure inside the droplets. Mol. dynamics simulations confirm that pressure-dependent interparticle potentials affect the self-assembly route of the confined particles. Optical spectrometry, small-angle X-ray scattering and electron microscopy are used to compare expts. and simulations and confirm that the onset of self-assembly depends on particle size and pressure. The overall formation mechanism reminds of the demixing of binary alloys with different phase diagrams.
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  70. 70
    Tang, Y.; Gomez, L.; Lesage, A.; Marino, E.; Kodger, T. E.; Meijer, J. M.; Kolpakov, P.; Meng, J.; Zheng, K.; Gregorkiewicz, T.; Schall, P. Highly Stable Perovskite Supercrystals via Oil-in-Oil Templating. Nano Lett. 2020, 20, 5997– 6004,  DOI: 10.1021/acs.nanolett.0c02005
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    70
    Highly Stable Perovskite Supercrystals via Oil-in-Oil Templating
    Tang, Yingying; Gomez, Leyre; Lesage, Arnon; Marino, Emanuele; Kodger, Thomas E.; Meijer, Janne-Mieke; Kolpakov, Paul; Meng, Jie; Zheng, Kaibo; Gregorkiewicz, Tom; Schall, Peter
    Nano Letters (2020), 20 (8), 5997-6004CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
    The large-scale assembly control of spherical, cubic, and hexagonal supercrystals (SCs) of inorg. perovskite nanocrystals (NCs) through templating by oil-in-oil emulsions is reported. An interplay between the roundness of the cubic NCs and the tension of the confining droplet surface sets the superstructure morphol., and this interplay is exploited to design dense hyperlattices of SCs. The SC films show strongly enhanced stability for ≥2 mo without obvious structural degrdn. and minor optical changes. The results on the controlled large-scale assembly of perovskite NC superstructures provide new prospects for the bottom-up prodn. of optoelectronic devices based on the microfluidic prodn. of mesoscopic building blocks.
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  71. 71
    Wang, D.; van der Wee, E. B.; Zanaga, D.; Altantzis, T.; Wu, Y.; Dasgupta, T.; Dijkstra, M.; Murray, C. B.; Bals, S.; van Blaaderen, A. Quantitative 3D Real-Space Analysis of Laves Phase Supraparticles. Nat. Commun. 2021, 12, 3980,  DOI: 10.1038/s41467-021-24227-0
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    71
    Quantitative 3D real-space analysis of Laves phase supraparticles
    Wang, Da; van der Wee, Ernest B.; Zanaga, Daniele; Altantzis, Thomas; Wu, Yaoting; Dasgupta, Tonnishtha; Dijkstra, Marjolein; Murray, Christopher B.; Bals, Sara; van Blaaderen, Alfons
    Nature Communications (2021), 12 (1), 3980CODEN: NCAOBW; ISSN:2041-1723. (Nature Research)
    Assembling binary mixts. of nanoparticles into crystals, gives rise to collective properties depending on the crystal structure and the individual properties of both species. However, quant. 3D real-space anal. of binary colloidal crystals with a thickness of more than 10 layers of particles has rarely been performed. Here we demonstrate that an excess of one species in the binary nanoparticle mixt. suppresses the formation of icosahedral order in the self-assembly in droplets, allowing the study of bulk-like binary crystal structures with a spherical morphol. also called supraparticles. As example of the approach, we show single-particle level anal. of over 50 layers of Laves phase binary crystals of hard-sphere-like nanoparticles using electron tomog. We observe a cryst. lattice composed of a random mixt. of the Laves phases. The no. ratio of the binary species in the crystal lattice matches that of a perfect Laves crystal. Our methodol. can be applied to study the structure of a broad range of binary crystals, giving insights into the structure formation mechanisms and structure-property relations of nanomaterials.
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  72. 72
    Montanarella, F.; Geuchies, J. J.; Dasgupta, T.; Prins, P. T.; van Overbeek, C.; Dattani, R.; Baesjou, P.; Dijkstra, M.; Petukhov, A. V.; van Blaaderen, A.; Vanmaekelbergh, D. Crystallization of Nanocrystals in Spherical Confinement Probed by in Situ X-ray Scattering. Nano Lett. 2018, 18, 3675– 3681,  DOI: 10.1021/acs.nanolett.8b00809
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    72
    Crystallization of Nanocrystals in Spherical Confinement Probed by in Situ X-ray Scattering
    Montanarella, Federico; Geuchies, Jaco J.; Dasgupta, Tonnishtha; Prins, P. Tim; van Overbeek, Carlo; Dattani, Rajeev; Baesjou, Patrick; Dijkstra, Marjolein; Petukhov, Andrei V.; van Blaaderen, Alfons; Vanmaekelbergh, Daniel
    Nano Letters (2018), 18 (6), 3675-3681CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
    The formation of supraparticles from nanocrystals confined in slowly evapg. oil droplets in an oil-in-H2O emulsion was studied. The nanocrystals consist of an FeO core, a CoFe2O4 shell, and oleate capping ligands, with an overall diam. of 12.5 nm. In situ small- and wide-angle x-ray scattering expts. were performed during the entire period of solvent evapn. and colloidal crystn. A slow increase in the vol. fraction of nanocrystals inside the oil droplets up to 20%, at which a sudden crystn. occurs was obsd. The computer simulations show that crystn. at such a low vol. fraction is only possible if attractive interactions between colloidal nanocrystals are taken into account in the model as well. The spherical supraparticles have a diam. of ∼700 nm and consist of a few cryst. fcc. domains. Nanocrystal supraparticles bear importance for magnetic and optoelectronic applications, such as color tunable biolabels, color tunable phosphors in LEDs, and miniaturized lasers.
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  73. 73
    Becker, M. A.; Vaxenburg, R.; Nedelcu, G.; Sercel, P. C.; Shabaev, A.; Mehl, M. J.; Michopoulos, J. G.; Lambrakos, S. G.; Bernstein, N.; Lyons, J. L.; Stöferle, T.; Mahrt, R. F.; Kovalenko, M. V.; Norris, D. J.; Rainò, G.; Efros, A. L. Bright Triplet Excitons in Caesium Lead Halide Perovskites. Nature 2018, 553, 189– 193,  DOI: 10.1038/nature25147
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    73
    Bright triplet excitons in caesium lead halide perovskites
    Becker, Michael A.; Vaxenburg, Roman; Nedelcu, Georgian; Sercel, Peter C.; Shabaev, Andrew; Mehl, Michael J.; Michopoulos, John G.; Lambrakos, Samuel G.; Bernstein, Noam; Lyons, John L.; Stoferle, Thilo; Mahrt, Rainer F.; Kovalenko, Maksym V.; Norris, David J.; Raino, Gabriele; Efros, Alexander L.
    Nature (London, United Kingdom) (2018), 553 (7687), 189-193CODEN: NATUAS; ISSN:0028-0836. (Nature Research)
    Nanostructured semiconductors emit light from electronic states known as excitons. For org. materials, Hund's rules state that the lowest-energy exciton is a poorly emitting triplet state. For inorg. semiconductors, similar rules predict an analog of this triplet state known as the 'dark exciton'. Because dark excitons release photons slowly, hindering emission from inorg. nanostructures, materials that disobey these rules have been sought. However, despite considerable exptl. and theor. efforts, no inorg. semiconductors have been identified in which the lowest exciton is bright. Here we show that the lowest exciton in caesium lead halide perovskites (CsPbX3, with X = Cl, Br or I) involves a highly emissive triplet state. We first use an effective-mass model and group theory to demonstrate the possibility of such a state existing, which can occur when the strong spin-orbit coupling in the conduction band of a perovskite is combined with the Rashba effect. We then apply our model to CsPbX3 nanocrystals, and measure size- and compn.-dependent fluorescence at the single-nanocrystal level. The bright triplet character of the lowest exciton explains the anomalous photon-emission rates of these materials, which emit about 20 and 1,000 times faster than any other semiconductor nanocrystal at room and cryogenic temps., resp. The existence of this bright triplet exciton is further confirmed by anal. of the fine structure in low-temp. fluorescence spectra. For semiconductor nanocrystals, which are already used in lighting, lasers and displays, these excitons could lead to materials with brighter emission. More generally, our results provide criteria for identifying other semiconductors that exhibit bright excitons, with potential implications for optoelectronic devices.
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  74. 74
    Becker, M. A.; Scarpelli, L.; Nedelcu, G.; Raino, G.; Masia, F.; Borri, P.; Stoferle, T.; Kovalenko, M. V.; Langbein, W.; Mahrt, R. F. Long Exciton Dephasing Time and Coherent Phonon Coupling in CsPbBr2Cl Perovskite Nanocrystals. Nano Lett. 2018, 18, 7546– 7551,  DOI: 10.1021/acs.nanolett.8b03027
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    74
    Long Exciton Dephasing Time and Coherent Phonon Coupling in CsPbBr2Cl Perovskite Nanocrystals
    Becker, Michael A.; Scarpelli, Lorenzo; Nedelcu, Georgian; Raino, Gabriele; Masia, Francesco; Borri, Paola; Stoferle, Thilo; Kovalenko, Maksym V.; Langbein, Wolfgang; Mahrt, Rainer F.
    Nano Letters (2018), 18 (12), 7546-7551CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
    Fully inorg. cesium lead halide perovskite nanocrystals (NCs) have shown to exhibit outstanding optical properties such as wide spectral tunability, high quantum yield, high oscillator strength as well as blinking-free single photon emission, and low spectral diffusion. Here, we report measurements of the coherent and incoherent exciton dynamics on the 100 fs to 10 ns time scale, detg. dephasing and d. decay rates in these NCs. The expts. are performed on CsPbBr2Cl NCs using transient resonant three-pulse four-wave mixing (FWM) in heterodyne detection at temps. ranging from 5 to 50 K. We found a low-temp. exciton dephasing time of 24.5 ± 1.0 ps, inferred from the decay of the photon-echo amplitude at 5 K, corresponding to a homogeneous line width (fwhm) of 54 ± 5 μeV. Furthermore, oscillations in the photon-echo signal on a picosecond time scale are obsd. and attributed to coherent coupling of the exciton to a quantized phonon mode with 3.45 meV energy.
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  75. 75
    Hestand, N. J.; Spano, F. C. Expanded Theory of H- and J-Molecular Aggregates: The Effects of Vibronic Coupling and Intermolecular Charge Transfer. Chem. Rev. 2018, 118, 7069– 7163,  DOI: 10.1021/acs.chemrev.7b00581
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    75
    Expanded Theory of H- and J-Molecular Aggregates: Effects of Vibronic Coupling and Intermolecular Charge Transfer
    Hestand, Nicholas J.; Spano, Frank C.
    Chemical Reviews (Washington, DC, United States) (2018), 118 (15), 7069-7163CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
    A review. The electronic excited states of mol. aggregates and their photophys. signatures have long fascinated spectroscopists and theoreticians alike since the advent of Frenkel exciton theory almost 90 years ago. The influence of mol. packing on basic optical probes like absorption and photoluminescence was originally worked out by Kasha for aggregates dominated by Coulombic intermol. interactions, eventually leading to the classification of J- and H-aggregates. This review outlines advances made in understanding the relationship between aggregate structure and photophysics when vibronic coupling and intermol. charge transfer are incorporated. An assortment of packing geometries is considered from the humble mol. dimer to more exotic structures including linear and bent aggregates, two-dimensional herringbone and "HJ" aggregates, and chiral aggregates. The interplay between long-range Coulomb coupling and short-range charge-transfer-mediated coupling strongly depends on the aggregate architecture leading to a wide array of photophys. behaviors.
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  76. 76
    Yaffe, O.; Guo, Y.; Tan, L. Z.; Egger, D. A.; Hull, T.; Stoumpos, C. C.; Zheng, F.; Heinz, T. F.; Kronik, L.; Kanatzidis, M. G.; Owen, J. S.; Rappe, A. M.; Pimenta, M. A.; Brus, L. E. Local Polar Fluctuations in Lead Halide Perovskite Crystals. Phys. Rev. Lett. 2017, 118, 136001,  DOI: 10.1103/PhysRevLett.118.136001
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    76
    Local polar fluctuations in lead halide perovskite crystals
    Yaffe, Omer; Guo, Yinsheng; Tan, Liang Z.; Egger, David A.; Hull, Trevor; Stoumpos, Constantinos C.; Zheng, Fan; Heinz, Tony F.; Kronik, Leeor; Kanatzidis, Mercouri G.; Owen, Jonathan S.; Rappe, Andrew M.; Pimenta, Marcos A.; Brus, Louis E.
    Physical Review Letters (2017), 118 (13), 136001/1-136001/6CODEN: PRLTAO; ISSN:1079-7114. (American Physical Society)
    Hybrid lead-halide perovskites have emerged as an excellent class of photovoltaic materials. Recent reports suggest that the org. mol. cation is responsible for local polar fluctuations that inhibit carrier recombination. We combine low-frequency Raman scattering with first-principles mol. dynamics (MD) to study the fundamental nature of these local polar fluctuations. Our observations of a strong central peak in the cubic phase of both hybrid (CH3NH3PbBr3) and all-inorg. (CsPbBr3) leadhalide perovskites show that anharmonic, local polar fluctuations are intrinsic to the general lead-halide perovskite structure, and not unique to the dipolar org. cation. MD simulations indicate that head-tohead Cs motion coupled to Br face expansion, occurring on a few hundred femtosecond time scale, drives the local polar fluctuations in CsPbBr3.
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  77. 77
    Lanigan-Atkins, T.; He, X.; Krogstad, M. J.; Pajerowski, D. M.; Abernathy, D. L.; Xu, G.; Xu, Z.; Chung, D. Y.; Kanatzidis, M. G.; Rosenkranz, S.; Osborn, R.; Delaire, O. Two-Dimensional Overdamped Fluctuations of the Soft Perovskite Lattice in CsPbBr3. Nat. Mater. 2021, 20, 977– 983,  DOI: 10.1038/s41563-021-00947-y
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    77
    Two-dimensional overdamped fluctuations of the soft perovskite lattice in CsPbBr3
    Lanigan-Atkins, T.; He, X.; Krogstad, M. J.; Pajerowski, D. M.; Abernathy, D. L.; Xu, Guangyong N. M. N.; Xu, Zhijun; Chung, D.-Y.; Kanatzidis, M. G.; Rosenkranz, S.; Osborn, R.; Delaire, O.
    Nature Materials (2021), 20 (7), 977-983CODEN: NMAACR; ISSN:1476-1122. (Nature Portfolio)
    Lead halide perovskites exhibit structural instabilities and large at. fluctuations thought to impact their optical and thermal properties, yet detailed structural and temporal correlations of their at. motions remain poorly understood. Here, these correlations are resolved in CsPbBr3 crystals using momentum-resolved neutron and X-ray scattering measurements as a function of temp., complemented with first-principles simulations. We uncover a striking network of diffuse scattering rods, arising from the liq.-like damping of low-energy Br-dominated phonons, reproduced in our simulations of the anharmonic phonon self-energy. These overdamped modes cover a continuum of wave vectors along the edges of the cubic Brillouin zone, corresponding to two-dimensional sheets of correlated rotations in real space, and could represent precursors to proposed two-dimensional polarons. Further, these motions directly impact the electronic gap edge states, linking soft anharmonic lattice dynamics and optoelectronic properties. These results provide insights into the highly unusual at. dynamics of halide perovskites, relevant to further optimization of their optical and thermal properties.
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  78. 78
    Baranov, D.; Fieramosca, A.; Yang, R. X.; Polimeno, L.; Lerario, G.; Toso, S.; Giansante, C.; Giorgi, M.; Tan, L. Z.; Sanvitto, D.; Manna, L. Aging of Self-Assembled Lead Halide Perovskite Nanocrystal Superlattices: Effects on Photoluminescence and Energy Transfer. ACS Nano 2021, 15, 650– 664,  DOI: 10.1021/acsnano.0c06595
    Google Scholar
    78
    Aging of Self-Assembled Lead Halide Perovskite Nanocrystal Superlattices: Effects on Photoluminescence and Energy Transfer
    Baranov, Dmitry; Fieramosca, Antonio; Yang, Ruo Xi; Polimeno, Laura; Lerario, Giovanni; Toso, Stefano; Giansante, Carlo; Giorgi, Milena De; Tan, Liang Z.; Sanvitto, Daniele; Manna, Liberato
    ACS Nano (2021), 15 (1), 650-664CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
    Excitonic coupling, electronic coupling, and cooperative interactions in self-assembled lead halide perovskite nanocrystals were reported to give rise to a red-shifted collective emission peak with accelerated dynamics. Here, we report that similar spectroscopic features could appear as a result of the nanocrystal reactivity within the self-assembled superlattices. This is demonstrated by studying CsPbBr3 nanocrystal superlattices over time with room-temp. and cryogenic micro-photoluminescence spectroscopy, X-ray diffraction, and electron microscopy. It is shown that a gradual contraction of the superlattices and subsequent coalescence of the nanocrystals occurs over several days of keeping such structures under vacuum. As a result, a narrow, low-energy emission peak is obsd. at 4 K with a concomitant shortening of the photoluminescence lifetime due to the energy transfer between nanocrystals. When exposed to air, self-assembled CsPbBr3 nanocrystals develop bulk-like CsPbBr3 particles on top of the superlattices. At 4 K, these particles produce a distribution of narrow, low-energy emission peaks with short lifetimes and excitation fluence-dependent, oscillatory decays. Overall, the aging of CsPbBr3 nanocrystal assemblies dramatically alters their emission properties and that should not be overlooked when studying collective optoelectronic phenomena nor confused with superfluorescence effects.
    >> More from SciFinder ®
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  79. 79
    De Roo, J.; Ibanez, M.; Geiregat, P.; Nedelcu, G.; Walravens, W.; Maes, J.; Martins, J. C.; Van Driessche, I.; Kovalenko, M. V.; Hens, Z. Highly Dynamic Ligand Binding and Light Absorption Coefficient of Cesium Lead Bromide Perovskite Nanocrystals. ACS Nano 2016, 10, 2071– 2081,  DOI: 10.1021/acsnano.5b06295
    Google Scholar
    79
    Highly Dynamic Ligand Binding and Light Absorption Coefficient of Cesium Lead Bromide Perovskite Nanocrystals
    De Roo, Jonathan; Ibanez, Maria; Geiregat, Pieter; Nedelcu, Georgian; Walravens, Willem; Maes, Jorick; Martins, Jose C.; Van Driessche, Isabel; Kovalenko, Maksym V.; Hens, Zeger
    ACS Nano (2016), 10 (2), 2071-2081CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
    Lead halide perovskite materials have attracted significant attention in the context of photovoltaics and other optoelectronic applications, and recently, research efforts have been directed to nanostructured lead halide perovskites. Collodial nanocrystals (NCs) of cesium lead halides (CsPbX3, X = Cl, Br, I) exhibit bright photoluminescence, with emission tunable over the entire visible spectral region. However, previous studies on CsPbX3 NCs did not address key aspects of their chem. and photophysics such as surface chem. and quant. light absorption. Here, we elaborate on the synthesis of CsPbBr3 NCs and their surface chem. In addn., the intrinsic absorption coeff. was detd. exptl. by combining elemental anal. with accurate optical absorption measurements. 1H soln. NMR spectroscopy was used to characterize sample purity, elucidate the surface chem., and evaluate the influence of purifn. methods on the surface compn. We find that ligand binding to the NC surface is highly dynamic, and therefore, ligands are easily lost during the isolation and purifn. procedures. However, when a small amt. of both oleic acid and oleylamine is added, the NCs can be purified, maintaining optical, colloidal, and material integrity. In addn., we find that a high amine content in the ligand shell increases the quantum yield due to the improved binding of the carboxylic acid.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhtV2nurY%253D&md5=5705ed1b4bef56397b3ab8e2d8c523be
  80. 80
    Ibanez, M.; Korkosz, R. J.; Luo, Z.; Riba, P.; Cadavid, D.; Ortega, S.; Cabot, A.; Kanatzidis, M. G. Electron Doping in Bottom-Up Engineered Thermoelectric Nanomaterials through HCl-Mediated Ligand Displacement. J. Am. Chem. Soc. 2015, 137, 4046– 4049,  DOI: 10.1021/jacs.5b00091
    Google Scholar
    80
    Electron Doping in Bottom-Up Engineered Thermoelectric Nanomaterials through HCl-Mediated Ligand Displacement
    Ibanez, Maria; Korkosz, Rachel J.; Luo, Zhishan; Riba, Pau; Cadavid, Doris; Ortega, Silvia; Cabot, Andreu; Kanatzidis, Mercouri G.
    Journal of the American Chemical Society (2015), 137 (12), 4046-4049CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
    A simple and effective method to introduce precise amts. of doping in nanomaterials produced from the bottom-up assembly of colloidal nanoparticles (NPs) is described. The procedure takes advantage of a ligand displacement step to incorporate controlled concns. of halide ions while removing carboxylic acids from the NP surface. Upon consolidation of the NPs into dense pellets, halide ions diffuse within the crystal structure, doping the anion sublattice and achieving n-type elec. doping. Through the characterization of the thermoelec. properties of nanocryst. PbS, the authors demonstrate this strategy to be effective to control charge transport properties on thermoelec. nanomaterials assembled from NP building blocks. This approach is subsequently extended to PbTexSe1-x@PbS core-shell NPs, where a significant enhancement of the thermoelec. figure of merit is achieved.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXktlCjt7o%253D&md5=5d312076294a0902e4057a65220259e5
  81. 81
    Kremer, J. R.; Mastronarde, D. N.; McIntosh, J. R. Computer Visualization of Three-Dimensional Image Data Using IMOD. J. Struct. Biol. 1996, 116, 71– 76,  DOI: 10.1006/jsbi.1996.0013
    Google Scholar
    81
    Computer visualization of three-dimensional image data using IMOD
    Kremer J R; Mastronarde D N; McIntosh J R
    Journal of structural biology (1996), 116 (1), 71-6 ISSN:1047-8477.
    We have developed a computer software package, IMOD, as a tool for analyzing and viewing three-dimensional biological image data. IMOD is useful for studying and modeling data from tomographic, serial section, and optical section reconstructions. The software allows image data to be visualized by several different methods. Models of the image data can be visualized by volume or contour surface rendering and can yield quantitative information.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADyaK28zmtFyqtg%253D%253D&md5=b6ab779bdec60f8644e254124c4dbbe7
  82. 82
    Amenitsch, H.; Bernstorff, S.; Laggner, P. High-Flux Beamline for Small-Angle X-Ray Scattering at ELETTRA. Rev. Sci. Instrum. 1995, 66, 1624– 1626,  DOI: 10.1063/1.1145864
    Google Scholar
    82
    High-flux beamline for small-angle x-ray scattering at ELETTRA
    Amenitsch, H.; Bernstorff, S.; Laggner, P.
    Review of Scientific Instruments (1995), 66 (2, Pt. 2), 1624-6CODEN: RSINAK; ISSN:0034-6748. (American Institute of Physics)
    The optical layout and the expected performance of the new high-flux SAXS beamline at ELETTRA is presented. From the high-power wiggler spectrum the 3 discrete energies 5.4, 8, and 16 keV will be selected with a double-crystal monochromator which contains 3 pairs of sepd. asym. cut plane Si(111) crystals. Downstream, the beam will be focused by a torodial mirror. The optical axis of the beamline will be horizontally 1.25 mrad off wiggler axis and the beamline will accept ∼1 mrad horizontally and 0.3 mrad vertically. The beamline will operate with a SAXS resoln. between 10 and a least 1000 Å in d spacing at 8 keV and was optimized with respect to extreme flux. A flux at the sample in the order of 1013 ph/s is expected for 8 keV photons (2 GeV, 400 mA). It will be possible to perform wide angle scattering measurements in the range of 3.5 and 7 Å d spacing at 8 keV simultaneously.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2MXktVOntLc%253D&md5=b1edecfc3334a7b5b0001435d6b064fe
  83. 83
    Ilavsky, J. Nika: Software for Two-Dimensional Data Reduction. J. Appl. Crystallogr. 2012, 45, 324– 328,  DOI: 10.1107/S0021889812004037
    Google Scholar
    83
    Nika: software for two-dimensional data reduction
    Ilavsky, Jan
    Journal of Applied Crystallography (2012), 45 (2), 324-328CODEN: JACGAR; ISSN:0021-8898. (International Union of Crystallography)
    Nika is an Igor Pro-based package for correction, calibration and redn. of two-dimensional area-detector data into one-dimensional data ('lineouts'). It is free (although the user needs a paid license for Igor Pro), open source and highly flexible. While typically used for small-angle X-ray scattering (SAXS) data, it can also be used for grazing-incidence SAXS data, wide-angle diffraction data and even small-angle neutron scattering data. It has been widely available to the user community since about 2005, and it is currently used at the SAXS instruments of selected large-scale facilities as their main data redn. package. It is, however, also suitable for desktop instruments when the manufacturer's software is not available or appropriate. Since it is distributed as source code, it can be scrutinized, verified and modified by users to suit their needs.
    >> More from SciFinder ®
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  84. 84
    Jiang, Z. GIXSGUI: a MATLAB Toolbox for Grazing-Incidence X-ray Scattering Data Visualization and Reduction, and Indexing of Buried Three-Dimensional Periodic Nanostructured Films. J. Appl. Crystallogr. 2015, 48, 917– 926,  DOI: 10.1107/S1600576715004434
    Google Scholar
    84
    GIXSGUI: a MATLAB toolbox for grazing-incidence X-ray scattering data visualization and reduction, and indexing of buried three-dimensional periodic nanostructured films
    Jiang, Zhang
    Journal of Applied Crystallography (2015), 48 (3), 917-926CODEN: JACGAR; ISSN:1600-5767. (International Union of Crystallography)
    GIXSGUI is a MATLAB toolbox that offers both a graphical user interface and script-based access to visualize and process grazing-incidence X-ray scattering data from nanostructures on surfaces and in thin films. It provides routine surface scattering data redn. methods such as geometric correction, one-dimensional intensity linecut, two-dimensional intensity reshaping etc. Three-dimensional indexing is also implemented to det. the space group and lattice parameters of buried organized nanoscopic structures in supported thin films.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXpsFaltL4%253D&md5=11025d56231bc1354cfc09c7692bba9c

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  21. Mitsuaki Yamauchi, Naoki Kubo, Naoki Aratani, Hiroko Yamada, Sadahiro Masuo. Controlled coaggregation pathways of perovskite nanocrystals and supramolecular dye assemblies. 2023https://doi.org/10.21203/rs.3.rs-3435503/v1
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  25. Weiqiu Kang, Xianhe Gao, Hongbo Li, Yang Wei, Chao Wang, Ziqi Tian. Hierarchical Chiral Self‐Assembly of Lead Halide Perovskite Nanocrystals by Oriented Phase Transition. Advanced Functional Materials 2023, 33 (30) https://doi.org/10.1002/adfm.202300388
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  27. Danni Yan, Qingsong Shan, Yuhui Dong, Lu Han, Xinli Wu, Yi Peng, Haibo Zeng. Perovskite nanocrystal superlattices: self-assembly, collective behavior, and applications. Chemical Communications 2023, 59 (36) , 5365-5374. https://doi.org/10.1039/D2CC06534G
  28. Zhuang Liu, Xian Qin, Qihao Chen, Tianci Jiang, Qiushui Chen, Xiaogang Liu. Metal–Halide Perovskite Nanocrystal Superlattice: Self‐Assembly and Optical Fingerprints. Advanced Materials 2023, 35 (16) https://doi.org/10.1002/adma.202209279
  29. Elena Shevchenko. Multicomponent nanoparticle superlattices. 2023, 298-323. https://doi.org/10.1016/B978-0-12-822425-0.00112-3
  30. Atanu Jana, Abhishek Meena, Supriya A. Patil, Yongcheol Jo, Sangeun Cho, Youngsin Park, Vijaya Gopalan Sree, Hyungsang Kim, Hyunsik Im, Robert A. Taylor. Self-assembly of perovskite nanocrystals. Progress in Materials Science 2022, 129 , 100975. https://doi.org/10.1016/j.pmatsci.2022.100975
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  • Abstract

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    Figure 1

    Figure 1. Diversity of binary and ternary SLs obtained from 5.3 and 8.6 nm CsPbBr3 nanocubes combined with 11.2–25.1 nm spherical Fe3O4 and NaGdF4 NCs, 10.7–11.7 nm truncated cuboid PbS NCs, thick NaGdF4 disks (31.5 nm in diameter and 18.5 nm thick), and 6.5–28.4 nm disk-shaped LaF3 NCs. Structures in solid and dashed frames were obtained with 8.6 and 5.3 nm CsPbBr3 NCs, respectively. HAADF-STEM image illustrates a sharp shape of a CsPbBr3 nanocube. The graph is a space-filling analysis within a hard-particle model for NaCl-, AlB2-, and AB2- and within OTM for ABO3- and ABO6-type SLs comprising larger spherical and smaller cubic NCs; the dashed line corresponds to the density of fcc packing of spherical NCs.

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    Figure 2

    Figure 2. Binary NaCl-type SL. (a) TEM image, (upper right inset) HAADF-STEM image, along with the corresponding (bottom inset) small-angle and (b) wide-angle ED patterns of a SL domain in [001]SL orientation assembled from 8.6 nm CsPbBr3 cubes and 18.6 nm NaGdF4 NCs. The upper left inset in (a) represents the NaCl-type unit cell according to the preferential cube’s orientation.

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    Figure 3

    Figure 3. Binary and ternary ABO3-type SLs. (a) TEM image along with (b) HAADF-STEM image, (c) the corresponding wide-angle ED pattern, and (d) SEM images of the [001]SL-oriented b-ABO3-type domains assembled from 8.6 nm CsPbBr3 cubes and 16.5 nm NaGdF4 spheres. (e, h) AFM height images of spheres- and cubes-terminated b-ABO3-type domains, respectively, along with (f, i) the height analysis of the profiles indicated in (e, h), (g, j) AFM three-dimensional images with the respective models. (k) TEM image along with (l) HAADF-STEM image, (m) the corresponding wide-angle ED pattern, and (n) SEM image of the [001]SL-oriented b-ABO3-type domains assembled from 8.6 nm CsPbBr3 cubes and 19.8 nm Fe3O4 spheres. (o) TEM image along with (p) HAADF-STEM image and (q) the corresponding wide-angle ED pattern of the [001]-oriented t-ABO3-type SL domains assembled from 8.6 nm CsPbBr3 cubes, 11.7 nm PbS truncated cuboids, and 21.5 nm Fe3O4 spheres. (r) HAADF-STEM image of a t-ABO3-type SL domain in [111]SL orientation assembled from 8.6 nm CsPbBr3, 11.7 nm PbS, and 25.1 nm Fe3O4 NCs; upper inset shows the model of [111]SL-oriented t-ABO3 unit cell, and lower inset shows small-angle ED pattern. Insets in (a, k, o) represent binary and ternary ABO3-type lattices according to the preferential NCs orientations, with Fe3O4 shown as gray spheres, NaGdF4 as yellowish spheres, CsPbBr3 as blue cubes, and PbS as red truncated cubes. The origin of wide-angle ED reflections in (c, m, q) is color-coded to match the NCs in insets.

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    Figure 4

    Figure 4. Binary AlB2-type SLs obtained combining 8.6 nm CsPbBr3 with (a–e) 19.8 nm Fe3O4 and (f–j) 16.5 nm NaGdF4 NCs. (a, b) TEM and (c) HAADF-STEM images of a single domain in [120]SL orientation, along with the corresponding (d) small-angle and (e) wide-angle ED patterns. (f, g) TEM and (h) HAADF-STEM images of a single domain in [001]SL orientation, along with the corresponding (i) small-angle and (j) wide-angle ED patterns. Insets in (e, j) show the orientations of CsPbBr3 NCs in the SL domains with respect to the electron beam (normal to the image plane).

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    Figure 5

    Figure 5. Structural characterization of a binary AlB2-type SL comprising 5.3 nm CsPbBr3 and 12.5 nm Fe3O4 NCs. (a) TEM image of [120]SL-oriented domain; inset is the image at higher magnification. (b) Wide-angle ED pattern of a single SL domain in (a). (c) Two-dimensional GISAX scattering pattern, showing long-range order in AlB2-type binary domains. (d) The unit cell of AlB2-type SL. (e) Small-angle ED pattern of a domain shown in (a). (f) HAADF-STEM image of the [120]SL-oriented domain. (g) EDX-STEM maps for Fe (gray, K-line) and Pb (blue, L-line) of the [120]SL-oriented domain. (h, k, n) Crystallographic models of [120]SL, [001]SL, and [010]SL-oriented AlB2 lattice, respectively. (i, j) Low- and high-magnification TEM images of an [001]SL-oriented domain. (l, m) Low- and high-magnification TEM images of a [010]SL-oriented domain; insets in (i, l) are images obtained by template-matching analysis of corresponding TEM images.

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    Figure 6

    Figure 6. Possible relative orientations of CsPbBr3 nanocubes within AlB2-type SL and packing fractions predicted by OPM packing analysis according to the hard-particle model. In both orientations, the body-diagonal of the cubes is parallel to the c-axis of the hexagonal SL unit cell, that is, [001]SL. In orientation “O1”, the cubes are mutually rotated by 60°, whereas in orientation “O2”, they are identically aligned. A significant increase in the packing fraction can be achieved if the B-cubes in orientation “O2” are not locked in the 2d Wyckoff positions, that is, are allowed to slide along the [001]SL (“O2 S3”). Wide-angle ED patterns from [120]SL- (see, for instance, Figures 4e and 5b) and [001]SL-oriented domains (Figure 5j) point to the alignment of all cubes with one body diagonal parallel to [001]SL and (110) CsPbBr3 planes are orthogonal to [010]SL. Hence these two orientations can be proposed. Experimentally, however, there exists no evidence to differentiate between these two structures, and hence both were considered for the analysis of lattice parameters and packing densities. Excluded is also a substantial orientational disorder in any dimension.

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    Figure 7

    Figure 7. An AB2-type binary SL assembled from CsPbBr3 nanocubes and Fe3O4 nanospheres. (a) TEM image of a SL assembled by 8.6 nm CsPbBr3 and 19.8 nm Fe3O4 NCs (γ = 0.414), along with the corresponding (inset) small-angle ED pattern, (b) HAADF-STEM image, and (c) wide-angle ED pattern. (d) Comparison of AlB2 (taken as orientation “O2”, see Figure 6) and AB2 structures. Red and green lines show the normals to (111) and (110) CsPbBr3 lattice planes, respectively, and indicate the directions of reflections in wide-angle ED patterns. (e) HAADF-STEM image showing grain boundary between AlB2 and AB2 binary SL domains. (f) Modeled crystallographic projections of cubic and spherical NCs in AB2 structure. (g) EDX-STEM elemental maps of an AB2-type binary SL assembled from 5.3 nm CsPbBr3 and 14.5 nm Fe3O4 NCs for Pb (blue, L-line) and Fe (red, K-line).

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    Figure 8

    Figure 8. Binary ABO6-type SLs obtained from 5.3 nm CsPbBr3 and 16.9 nm Fe3O4 NCs (γ = 0.315). (a) Wide-angle and (inset) small-angle ED patterns of [001]SL-oriented domain. (b) Space-filling analysis for b-ABO6-type SLs comprising larger spherical and smaller cubic (solid line) or spherical (blue dashed line) NCs within the hard-particle model, except for the indicated OTM branch. (c) Structural model of a b-ABO6-type unit cell and a slice through (002)SL. (d–f) HAADF-STEM images of [001]SL-, [111]SL-, and [101]SL-oriented domains and (g) the corresponding structural models of SL projections.

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    Figure 9

    Figure 9. Binary SLs self-assembled from the mixtures of 5.3 nm CsPbBr3 and 15.2 nm NaGdF4 NCs. Increasing the relative concentration of CsPbBr3 NCs changes the experiment outcome from (a–d) NaCl-type to (e–h) AlB2-type with (i–l) AB2-type and then to (m, n) ABO3-type SLs, as illustrated by (o) the scheme. (a, e, i, m) TEM images of [001]SL projections, along with the corresponding (bottom insets) small-angle ED and (b, f, j, n) wide-angle ED patterns; the respective high-magnification HAADF-STEM images are shown as upper insets. (c, d) HAADF images of [001]SL- and [111]SL-oriented domains. (g) TEM image of [120]SL-oriented domain, along with the corresponding (upper inset) HAADF-STEM image, (bottom inset) small-angle ED, and (h) wide-angle ED patterns. (k) Bright-field and (l) HAADF-STEM images of [001]SL-oriented domain.

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    Figure 10

    Figure 10. Characterization of b-ABO3-type SL assembled from 8.6 nm CsPbBr3 and 10.7–11.7 nm PbS. (a) HAADF-STEM image of a single [001]SL-oriented binary ABO3 domain comprising of 8.6 nm CsPbBr3 NCs and 11.7 nm PbS NCs. (b) TEM image of a single b-ABO3 domain in [001]SL orientation assembled from 8.6 nm CsPbBr3 NCs and 10.7 nm PbS NCs, together with the respective (c) small-angle and (d) wide-angle ED patterns. Diffraction arcs are colored to show their origin from CsPbBr3 and PbS NCs presented as insets. Inset in (a) shows the binary ABO3 lattice and illustrates the relative position and orientation of NCs. (e) Crystallographic model of a [001]SL-oriented ABO3 lattice, along with HAADF-STEM image and respective EDX-STEM maps for S (red, K-line), Pb (blue, L-line), Cs (green, L-line), and Br (yellow, K-line).

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    Figure 11

    Figure 11. NaCl-type binary SLs from 8.6 nm CsPbBr3 NCs combined with truncated cuboid PbS NCs. (a) TEM image of a monolayer domain. (b, c) HAADF-STEM images of SL domains with an increasing number of layers. (e, f) TEM images of [001]SL-oriented SL domains at different magnification, along with the (g) wide-angle and (h) small-angle ED patterns measured from the domain shown in (f); the reflections from CsPbBr3 and PbS NCs are colored to match the NCs in the structural model (d). Images from (a, c, f–h) were obtained with 10.7 nm PbS NCs (γ = 0.778) and from (b, e) with 11.7 nm PbS NCs (γ = 0.720).

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    Figure 12

    Figure 12. CuAu- and AlB2-type binary SLs assembled from truncated cuboid 10.7 nm PbS NCs and, respectively, 8.6 and 5.3 nm CsPbBr3 cubes. (a) TEM image of a single CuAu-type SL domain in [101]SL orientation, along with the corresponding (inset) small-angle ED and (b) wide-angle ED patterns (the origin of the reflections is color-coded to match the NCs in the model shown as inset). (c) CuAu unit cell and crystallographic model of [101]SL-oriented lattice assuming preferable orientations of NCs in agreement with ED. (d) HAADF-STEM images of a SL domain taken at 0° and 45° tilting angles around [010]SL that correspond to [101]SL and [001]SL orientations, respectively; crystallographic model of [001]SL-oriented CuAu-type lattice is depicted in the inset of (e). (f) EDX-STEM elemental maps recorded from a [001]SL-oriented domain shown in (e). (g) TEM image of AlB2-type SL with twist grain boundaries between [001]SL- (magnified in upper inset) and [010]SL-oriented (magnified in bottom inset) domains. (h) HAADF-STEM, high-magnification TEM image (upper inset), and crystallographic model (bottom inset) along with (i) wide-angle ED pattern of [120]SL-oriented AlB2-type SL. Bottom and upper ([120]SL orientation) insets in (i) represent the unit cell of AlB2-type SL with orientations of NCs that result in the most intense wide-angle ED spots marked in red (PbS) and blue (CsPbBr3).

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    Figure 13

    Figure 13. CaC2-like SL assembled from 8.6 nm CsPbBr3 nanocubes and 31.5 nm NaGdF4 thick nanodisks, featuring sets of two cubes on one lattice site. (a) TEM image and the SL models are shown as insets. (b) HAADF-STEM images at different magnifications, along with the corresponding (c) wide-angle ED and (inset) small-angle ED patterns. (d, e) SEM images at different magnifications.

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    Figure 14

    Figure 14. Binary SLs obtained from FAPbBr3 nanocubes. (a) TEM and HAADF-STEM (top right panel) images of a b-ABO3-type SL assembled from 9 nm FAPbBr3 and 19.5 nm NaGdF4 NCs; SL model is shown in the bottom right panel. (b, c) Bright-field STEM images of, respectively, an [120]-oriented AlB2-type and [001]SL-oriented AB2-type SL domains comprising 9 nm FAPbBr3 and 15.1 nm NaGdF4 NCs. (d) HAADF-STEM image of an [111]-oriented NaCl-type SL domain comprising 5.7 nm FAPbBr3 and 15.1 nm NaGdF4 NCs. (e) Bright-field STEM image of a columnar AB-type SL domain obtained from 5.7 nm FAPbBr3 NCs and 12.5 nm LaF3 nanodisks. (f) TEM and (g) HAADF-STEM images of lamellar SL obtained from 5.7 nm FAPbBr3 NCs and 12.5 nm LaF3 nanodisks; EDX-STEM elemental maps for La (magenta, L-line) and Pb (blue, L-line) are shown in the inset in (g). Insets in (b–d) are SL models.

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    Figure 15

    Figure 15. Self-assembly of perovskite NCs at the liquid–air interface. (a) Illustration of the assembly process: NCs dispersed in nonpolar solvents are cast onto the surface of glyceryl triacetate in a Teflon well or Petri dish, which is then covered with glass or larger Petri dish, respectively; ordered SL film floating on the subphase is formed upon evaporation the solvent. (b–d) TEM images of 9 nm CsPbBr3 NC monolayer obtained from octane on glyceryl triacetate. (e–g) TEM images of AB-type monolayer (obtained from dodecane) and NaCl- and AlB2-type films (obtained from decane), respectively, comprising 8.6 nm CsPbBr3 and 19.8 nm Fe3O4 NCs.

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    Figure 16

    Figure 16. Oil-in-oil templated assembly of binary SLs comprising perovskite NCs. (a) Illustration of the assembly process: NCs dispersed in toluene are mixed with a fluorinated solvent (FC-40) containing surfactant (008-FS) that is capable of stabilizing droplets with NCs. Slow evaporation of toluene from the droplets during stirring results in the formation of ordered binary supraparticles. (b) SEM and HAADF-STEM (right panel) images of supraparticles with b-ABO3 structure obtained from 8.6 nm CsPbBr3 cubic and 18.6 nm NaGdF4 spherical NCs. (c) SEM images of supraparticles with CaC2-like structure assembled from 8.6 nm CsPbBr3 nanocubes and 31.5 nm NaGdF4 thick nanodisks. Insets in (b, c) show the SL models.

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    Figure 17

    Figure 17. PL properties of ABO3-type binary SLs at 6 K. (a) PL spectra of binary ABO3-type SLs assembled by employing 8.6 nm CsPbBr3 and 19.5 nm (top) or 14.5 nm (bottom) Fe3O4 NCs. The PL spectra (black solid lines) are fitted to a doubled Lorentzian function (red and blue lines are the individual functions, while the gray lines are the cumulative fits to the experimental data). (b) Measured coupled vs uncoupled splitting energy for several samples with different distances between O-site and B-site NCs. Error bars denote the standard deviation obtained by measuring several PL spectra on different locations on the same sample.

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    Figure 18

    Figure 18. Impact of the temperature on the PL band from coupled NCs in AlB2-type binary SLs (5.3 nm CsPbBr3 NCs + 12.5 nm Fe3O4 NCs). (a) Normalized PL spectra for the AlB2-type SLs at 6 and 100 K. The inset reports a zoom-in PL spectrum for a nominally similar sample where much narrower emission peaks are resolved (full width at half-maximum of about 3 meV, dashed line). (b) Two-dimensional colored plot of normalized PL spectra obtained at different temperatures. (c) The relative amplitude of the two emission bands as a function of temperature (black open circles). The red solid line is the best fit to an Arrhenius plot returning activation energy of 14 meV, very close to the LO-phonon energy of CsPbBr3 crystal (17 meV). (d) Extracted splitting energy is plotted vs the squared root of the red-shifted peak area, exhibiting a linear dependence (solid red line).

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    Figure 19

    Figure 19. PL and absorbance spectra of binary ABO3-type SLs comprising 8.8 nm CsPbBr3 cubes and 18.2 nm (top panel) or 15.1 nm (middle panel) NaGdF4 spherical NCs, measured at 10 K (top and middle panel) and 200 K (bottom panel).

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  • References

    This article references 84 other publications.

    1. 1
      Boles, M. A.; Engel, M.; Talapin, D. V. Self-Assembly of Colloidal Nanocrystals: From Intricate Structures to Functional Materials. Chem. Rev. 2016, 116, 11220– 11289,  DOI: 10.1021/acs.chemrev.6b00196
      1
      Self-Assembly of Colloidal Nanocrystals: From Intricate Structures to Functional Materials
      Boles, Michael A.; Engel, Michael; Talapin, Dmitri V.
      Chemical Reviews (Washington, DC, United States) (2016), 116 (18), 11220-11289CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
      A review. Chem. methods developed over the past two decades enable prepn. of colloidal nanocrystals with uniform size and shape. These Brownian objects readily order into superlattices. Recently, the range of accessible inorg. cores and tunable surface chemistries dramatically increased, expanding the set of nanocrystal arrangements exptl. attainable. In this review, we discuss efforts to create next-generation materials via bottom-up organization of nanocrystals with preprogrammed functionality and self-assembly instructions. This process is often driven by both interparticle interactions and the influence of the assembly environment. The introduction provides the reader with a practical overview of nanocrystal synthesis, self-assembly, and superlattice characterization. We then summarize the theory of nanocrystal interactions and examine fundamental principles governing nanocrystal self-assembly from hard and soft particle perspectives borrowed from the comparatively established fields of micrometer colloids and block copolymer assembly. We outline the extensive catalog of superlattices prepd. to date using hydrocarbon-capped nanocrystals with spherical, polyhedral, rod, plate, and branched inorg. core shapes, as well as those obtained by mixing combinations thereof. We also provide an overview of structural defects in nanocrystal superlattices. We then explore the unique possibilities offered by leveraging nontraditional surface chemistries and assembly environments to control superlattice structure and produce nonbulk assemblies. We end with a discussion of the unique optical, magnetic, electronic, and catalytic properties of ordered nanocrystal superlattices, and the coming advances required to make use of this new class of solids.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhtlyisbnO&md5=274e85cfde9882c4a5f718ca0434e1dd
    2. 2
      Tan, R.; Zhu, H.; Cao, C.; Chen, O. Multi-Component Superstructures Self-Assembled from Nanocrystal Building Blocks. Nanoscale 2016, 8, 9944– 9961,  DOI: 10.1039/C6NR01662F
      2
      Multi-component superstructures self-assembled from nanocrystal building blocks
      Tan, Rui; Zhu, Hua; Cao, Can; Chen, Ou
      Nanoscale (2016), 8 (19), 9944-9961CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)
      More than three decades of intensive study to make high-quality nanocrystals have created a unique toolbox for building multi-component superstructures, which have been recognized as a new generation of metamaterials important to both fundamental sciences and applied technologies. This minireview summarizes recent advances in this exciting field. We will focus our discussion on the synthetic strategies and superstructures of this multi-component metamaterial, and highlight their novel properties and potential applications. Addnl., some perspectives on possible developments in this field are offered at the end of this review. We hope that this minireview will both inform and stimulate research interests for the design and fabrication of these nanocrystal-based multi-component metamaterials for diverse applications in the future.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xms1Wgtro%253D&md5=10379c2b1ee8d30ef92dd6aaf1912454
    3. 3
      Urban, J. J.; Talapin, D. V.; Shevchenko, E. V.; Kagan, C. R.; Murray, C. B. Synergism in Binary Nanocrystal Superlattices Leads to Enhanced P-Type Conductivity in Self-Assembled PbTe/Ag2Te Thin Films. Nat. Mater. 2007, 6, 115– 121,  DOI: 10.1038/nmat1826
      3
      Synergism in binary nanocrystal superlattices leads to enhanced p-type conductivity in self-assembled PbTe/Ag2Te thin films
      Urban, Jeffrey J.; Talapin, Dmitri V.; Shevchenko, Elena V.; Kagan, Cherie R.; Murray, Christopher B.
      Nature Materials (2007), 6 (2), 115-121CODEN: NMAACR; ISSN:1476-1122. (Nature Publishing Group)
      The ordered cocrystn. of nanoparticles into binary superlattices enables close contact of nanocrystals with distinct phys. properties, providing a route to 'metamaterials' design. Here the authors present the 1st electronic measurements of multicomponent nanocrystal solids composed of PbTe and Ag2Te, demonstrating synergistic effects leading to enhanced p-type cond. First, syntheses of size-tuneable PbTe and Ag2Te nanocrystals are presented, along with deposition as thin-film nanocrystal solids, whose electronic transport properties were characterized. Next, assembly of PbTe and Ag2Te nanocrystals into AB binary nanocrystal superlattices is demonstrated. Also, binary composites of varying PbTe-Ag2Te stoichiometry (1:1 and 5:1) were prepd. and electronically characterized. These composites show strongly enhanced (conductance ∼100-fold increased in 1:1 composites over the sum of individual conductances of single-component PbTe and Ag2Te films) p-type electronic cond. This observation, consistent with the role of Ag2Te as a p-type dopant in bulk PbTe, demonstrates that nanocrystals can behave as dopants in nanostructured assemblies.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXhtFyhsrw%253D&md5=88c92965e961ac22b0faa11aba67c8ce
    4. 4
      Chen, J.; Ye, X.; Oh, S. J.; Kikkawa, J. M.; Kagan, C. R.; Murray, C. B. Bistable Magnetoresistance Switching in Exchange-Coupled CoFe2O4-Fe3O4 Binary Nanocrystal Superlattices by Self-Assembly and Thermal Annealing. ACS Nano 2013, 7, 1478– 1486,  DOI: 10.1021/nn3052617
      4
      Bistable Magnetoresistance Switching in Exchange-Coupled CoFe2O4-Fe3O4 Binary Nanocrystal Superlattices by Self-Assembly and Thermal Annealing
      Chen, Jun; Ye, Xingchen; Oh, Soong Ju; Kikkawa, James M.; Kagan, Cherie R.; Murray, Christopher B.
      ACS Nano (2013), 7 (2), 1478-1486CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
      Self-assembly of multicomponent nanocrystal superlattices provides a modular approach to the design of metamaterials by choosing constituent nanocrystal building blocks with desired phys. properties and engineering the interparticle coupling. The authors report the self-assembly of binary nanocrystal superlattices composed of magnetically hard CoFe2O4 nanocrystals and magnetically soft Fe3O4 nanocrystals. Both NaZn13- and MgZn2-type CoFe2O4-Fe3O4 binary nanocrystal superlattices were formed by the liq.-air interfacial assembly approach. Exchange coupling is achieved in both types of binary superlattices after thermal annealing under vacuum at 400°. The exchange-coupled CoFe2O4-Fe3O4 binary nanocrystal superlattices show single-phase magnetization switching behavior and magnetoresistance switching behavior <200 K. The NaZn13-type CoFe2O4-Fe3O4 binary nanocrystal superlattices annealed at 500° even exhibit bistable magnetoresistance switching behavior at room temp. constituting a simple nonvolatile memory function.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXjslKl&md5=fb772c9528b9eccd7ae409e005bb48fc
    5. 5
      Ye, X.; Chen, J.; Diroll, B. T.; Murray, C. B. Tunable Plasmonic Coupling in Self-Assembled Binary Nanocrystal Superlattices Studied by Correlated Optical Microspectrophotometry and Electron Microscopy. Nano Lett. 2013, 13, 1291– 1297,  DOI: 10.1021/nl400052w
      5
      Tunable Plasmonic Coupling in Self-Assembled Binary Nanocrystal Superlattices Studied by Correlated Optical Microspectrophotometry and Electron Microscopy
      Ye, Xingchen; Chen, Jun; Diroll, Benjamin T.; Murray, Christopher B.
      Nano Letters (2013), 13 (3), 1291-1297CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
      The authors study the plasmonic properties of self-assembled binary nanocrystal superlattices (BNSLs) using correlated optical microspectrophotometry and electron microscopy performed on individual BNSL domains. The strength of near-field couplings between adjacent plasmonic nanocrystals (NCs) can be systematically engineered by varying the NC size, compn., and the lattice symmetry of BNSLs, leading to broadband spectral tunability of the collective plasmonic response of BNSLs across the entire visible spectrum. Self-assembled multicomponent NC superlattices represent a versatile platform for the rational design of macroscopic 3-dimensional plasmonic metamaterials with emergent optical characteristics.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXivVyiu7s%253D&md5=78668edb12cbb764692492d9eff59c08
    6. 6
      Talapin, D. V.; Shevchenko, E. V.; Kornowski, A.; Gaponik, N.; Haase, M.; Rogach, A. L.; Weller, H. A New Approach to Crystallization of CdSe Nanoparticles into Ordered Three-Dimensional Superlattices. Adv. Mater. 2001, 13, 1868– 1871,  DOI: 10.1002/1521-4095(200112)13:24<1868::AID-ADMA1868>3.0.CO;2-0
      6
      A new approach to crystallization of CdSe nanoparticles into ordered three-dimensional superlattices
      Talapin, Dmitri V.; Shevchenko, Elena V.; Kornowski, Andreas; Gaponik, Nikolai; Haase, Markus; Rogach, Andrey L.; Weller, Horst
      Advanced Materials (Weinheim, Germany) (2001), 13 (24), 1868-1871CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH)
      Two types of colloidal crystals consisting of CdSe nanocrystals were prepd. by the method of controlled oversatn. in solns. At 1st, the CdSe nanocrystals were prepd. from either trioctylphosphine oxide/trioctylphosphine (TOPO-TOP) or hexadecylamine (HDA)-TOPO-TOP mixts. starting from TOPSe and (Me2)Cd. Their growth was monitored by UV-vis absorption spectroscopy and the nanocrystals were redissolved in toluene. Then, a non-solvent (MeOH) was slowly introduced into the concd. soln. of the monodisperse CdSe nanocrystals in toluene. The diffusion of MeOH was carried out directly or through a buffer layer of a 3rd component (propan-2-ol). In the 1st case, irregular shaped crystals were obtained, while the slower diffusion through the buffer layer resulted in perfectly faceted hexagonal platelets with a size of 100 μm. The samples were characterized by XRD, high-resoln. TEM, optical microscopy, and absorption and photoluminescence spectroscopy. CdSe quantum dots were crystd. in vertically positioned glass tubes. Here, the CdSe nanocrystals were aligned in a regular fcc. 3D superlattice.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD38XjtVKlsA%253D%253D&md5=3a22bf4d9d418c43a3e530275211edd5
    7. 7
      Bodnarchuk, M. I.; Kovalenko, M. V.; Heiss, W.; Talapin, D. V. Energetic and Entropic Contributions to Self-Assembly of Binary Nanocrystal Superlattices: Temperature as the Structure-Directing Factor. J. Am. Chem. Soc. 2010, 132, 11967– 11977,  DOI: 10.1021/ja103083q
      7
      Energetic and Entropic Contributions to Self-Assembly of Binary Nanocrystal Superlattices: Temperature as the Structure-Directing Factor
      Bodnarchuk, Maryna I.; Kovalenko, Maksym V.; Heiss, Wolfgang; Talapin, Dmitri V.
      Journal of the American Chemical Society (2010), 132 (34), 11967-11977CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
      We studied the effect of temp. on self-assembly of monodisperse colloidal nanocrystals into single-component and binary superlattices. Temp., which serves as a weighting factor for the internal energy (U) and entropy (S) contributions to the Helmholtz free energy F = U - TS, allows tailoring relative wts. of the interparticle interactions and free-vol. entropy during the formation of nanocrystal superlattices. Temp. also provides a convenient tool for directing self-assembly of nanocrystals toward desired superlattice structures. We found that temp. strongly affects the structures of binary superlattices self-assembled from the mixts. of CdSe + PbS nanocrystals and PbSe + Pd nanocrystals. In the former case, small Hamaker consts. for CdSe and PbS nanocrystals led to a relatively simple phase diagram, including only high-d. NaZn13-, AlB2-, and NaCl-type binary superlattices. In contrast, binary superlattices self-assembled at different temps. from PbSe and Pd nanocrystals showed a no. of low-d. complex phases stabilized by strong local van der Waals interactions between Pd nanocrystals. The structural diversity of nanoparticle superlattices is shown to be a result of the cooperative effect of the entropy-driven crystn. and the interparticle interactions. Both ΔU and TΔS terms assocd. with the superlattice formation should be of the same order of magnitude, with |ΔU| < |TΔS| for the assembly of CdSe and PbS nanocrystals and |ΔU| > |TΔS| for the PbSe and Pd nanocrystals.
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    8. 8
      Boles, M. A.; Talapin, D. V. Self-Assembly of Tetrahedral CdSe Nanocrystals: Effective ″Patchiness″ via Anisotropic Steric Interaction. J. Am. Chem. Soc. 2014, 136, 5868– 5871,  DOI: 10.1021/ja501596z
      8
      Self-Assembly of Tetrahedral CdSe Nanocrystals: Effective "Patchiness" via Anisotropic Steric Interaction
      Boles, Michael A.; Talapin, Dmitri V.
      Journal of the American Chemical Society (2014), 136 (16), 5868-5871CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
      Self-assembled superlattices (SLs) comprised of tetrahedral nanocrystal (NCs) are described. Self-assembly of CdSe nanotetrahedra into an open structure (estd. space-filling fraction φ ≈ 0.59) was obsd. This finding highlights a gap in the understanding of the hierarchy of energy scales acting on colloidal NCs during self-assembly. A strong dependence of ligand-ligand interaction potential on NC surface curvature is proposed. This effect favors spatial proximity of vertices in the dense colloidal crystal and may be considered an emergent "patchiness" acting through chem. identical ligand mols.
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    9. 9
      Dong, A.; Chen, J.; Vora, P. M.; Kikkawa, J. M.; Murray, C. B. Binary Nanocrystal Superlattice Membranes Self-Assembled at the Liquid-Air Interface. Nature 2010, 466, 474– 477,  DOI: 10.1038/nature09188
      9
      Binary nanocrystal superlattice membranes self-assembled at the liquid-air interface
      Dong, Angang; Chen, Jun; Vora, Patrick M.; Kikkawa, James M.; Murray, Christopher B.
      Nature (London, United Kingdom) (2010), 466 (7305), 474-477CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)
      The spontaneous organization of multicomponent micrometer-sized colloids or nanocrystals into superlattices is of scientific importance for understanding the assembly process on the nanometer scale and is of great interest for bottom-up fabrication of functional devices. In particular, co-assembly of two types of nanocrystal into binary nanocrystal superlattices (BNSLs) has recently attracted significant attention, as this provides a low-cost, programmable way to design meta materials with precisely controlled properties that arise from the organization and interactions of the constituent nanocrystal components. Although challenging, the ability to grow and manipulate large-scale BNSLs is crit. for extensive exploration of this new class of material. The authors report a general method of growing centimeter-scale, uniform membranes of BNSLs that can readily be transferred to arbitrary substrates. The authors' method is based on the liq.-air interfacial assembly of multicomponent nanocrystals and circumvents the limitations assocd. with the current assembly strategies, allowing integration of BNSLs on any substrate for the fabrication of nanocrystal-based devices. The authors demonstrate the construction of magnetoresistive devices by incorporating large-area (1.5 mm × 2.5 mm) BNSL membranes; their magneto transport measurements clearly show that device magnetoresistance is dependent on the structure (stoichiometry) of the BNSLs. The ability to transfer BNSLs also allows the construction of free-standing membranes and other complex architectures that were not accessible previously.
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      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXptFGqtbo%253D&md5=09dad42e48f5c7c4b24cdb093274d196
    10. 10
      Paik, T.; Yun, H.; Fleury, B.; Hong, S. H.; Jo, P. S.; Wu, Y.; Oh, S. J.; Cargnello, M.; Yang, H.; Murray, C. B.; Kagan, C. R. Hierarchical Materials Design by Pattern Transfer Printing of Self-Assembled Binary Nanocrystal Superlattices. Nano Lett. 2017, 17, 1387– 1394,  DOI: 10.1021/acs.nanolett.6b04279
      10
      Hierarchical Materials Design by Pattern Transfer Printing of Self-Assembled Binary Nanocrystal Superlattices
      Paik, Taejong; Yun, Hongseok; Fleury, Blaise; Hong, Sung-Hoon; Jo, Pil Sung; Wu, Yaoting; Oh, Soong-Ju; Cargnello, Matteo; Yang, Haoran; Murray, Christopher B.; Kagan, Cherie R.
      Nano Letters (2017), 17 (3), 1387-1394CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
      We demonstrate the fabrication of hierarchical materials by controlling the structure of highly ordered binary nanocrystal superlattices (BNSLs) on multiple length scales. Combinations of magnetic, plasmonic, semiconducting, and insulating colloidal nanocrystal (NC) building blocks are self-assembled into BNSL membranes via the liq.-interfacial assembly technique. Free-standing BNSL membranes are transferred onto topog. structured poly(dimethylsiloxane) molds via the Langmuir-Schaefer technique and then deposited in patterns onto substrates via transfer printing. BNSLs with different structural motifs are successfully patterned into various meso- and microstructures such as lines, circles, and even three-dimensional grids across large-area substrates. A combination of electron microscopy and grazing incidence small-angle X-ray scattering (GISAXS) measurements confirm the ordering of NC building blocks in meso- and micropatterned BNSLs. This technique demonstrates structural diversity in the design of hierarchical materials by assembling BNSLs from NC building blocks of different compn. and size by patterning BNSLs into various size and shape superstructures of interest for a broad range of applications.
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    11. 11
      Ye, X.; Collins, J. E.; Kang, Y.; Chen, J.; Chen, D. T.; Yodh, A. G.; Murray, C. B. Morphologically Controlled Synthesis of Colloidal Upconversion Nanophosphors and Their Shape-Directed Self-Assembly. Proc. Natl. Acad. Sci. U. S. A. 2010, 107, 22430– 22435,  DOI: 10.1073/pnas.1008958107
      11
      Morphologically controlled synthesis of colloidal upconversion nanophosphors and their shape-directed self-assembly
      Ye, Xingchen; Collins, Joshua E.; Kang, Yijin; Chen, Jun; Chen, Daniel T. N.; Yodh, Arjun G.; Murray, Christopher B.
      Proceedings of the National Academy of Sciences of the United States of America (2010), 107 (52), 22430-22435, S22430/1-S22430/27CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)
      We report a one-pot chem. approach for the synthesis of highly monodisperse colloidal nanophosphors displaying bright upconversion luminescence under 980 nm excitation. This general method optimizes the synthesis with initial heating rates up to 100°/min generating a rich family of nanoscale building blocks with distinct morphologies (spheres, rods, hexagonal prisms, and plates) and upconversion emission tunable through the choice of rare earth dopants. Furthermore, we employ an interfacial assembly strategy to organize these nanocrystals (NCs) into superlattices over multiple length scales facilitating the NC characterization and enabling systematic studies of shape-directed assembly. The global and local ordering of these superstructures is programmed by the precise engineering of individual NC's size and shape. This dramatically improved nanophosphor synthesis together with insights from shape-directed assembly will advance the investigation of an array of emerging biol. and energy-related nanophosphor applications.
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    12. 12
      Wang, P. P.; Qiao, Q.; Zhu, Y.; Ouyang, M. Colloidal Binary Supracrystals with Tunable Structural Lattices. J. Am. Chem. Soc. 2018, 140, 9095– 9098,  DOI: 10.1021/jacs.8b05643
      12
      Colloidal Binary Supracrystals with Tunable Structural Lattices
      Wang, Peng-peng; Qiao, Qiao; Zhu, Yimei; Ouyang, Min
      Journal of the American Chemical Society (2018), 140 (29), 9095-9098CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
      Colloidal binary supracrystals (SCs) possessing tunable and ordered assembly of two different types of functional nanoparticles (NPs) represent a unique class of artificial materials for both fundamental study and technol. applications, but related study has been limited due to substantial challenges in materials growth. Here we report the controlled growth of colloidal binary SCs consisting of Au and Fe3O4 NPs via an oil-in-water emulsion process. The size, stoichiometry, and lattice structure of the SCs can be broadly tuned by the growth parameters. Furthermore, our growth method is general and applicable to other NP building blocks to achieve various functional binary SCs. These as-grown free-standing binary SCs should therefore enable new test beds for exploring different nanoscale interactions ranging from the formation and stability of nanoscale binary phase to the emerging magneto-plasmonic coupling physics.
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    13. 13
      de Nijs, B.; Dussi, S.; Smallenburg, F.; Meeldijk, J. D.; Groenendijk, D. J.; Filion, L.; Imhof, A.; van Blaaderen, A.; Dijkstra, M. Entropy-driven formation of large icosahedral colloidal clusters by spherical confinement. Nat. Mater. 2015, 14, 56– 60,  DOI: 10.1038/nmat4072
      13
      Entropy-driven formation of large icosahedral colloidal clusters by spherical confinement
      de Nijs, Bart; Dussi, Simone; Smallenburg, Frank; Meeldijk, Johannes D.; Groenendijk, Dirk J.; Filion, Laura; Imhof, Arnout; van Blaaderen, Alfons; Dijkstra, Marjolein
      Nature Materials (2015), 14 (1), 56-60CODEN: NMAACR; ISSN:1476-1122. (Nature Publishing Group)
      Icosahedral symmetry, which is not compatible with truly long-range order, can be found in many systems, such as liqs., glasses, at. clusters, quasicrystals, and virus-capsids. To obtain arrangements with a high degree of icosahedral order from tens of particles or more, interparticle attractive interactions are considered to be essential. The authors report that entropy and spherical confinement suffice for the formation of icosahedral clusters consisting of up to 100,000 particles. Specifically, by using real-space measurements on nanometer- and micrometer-sized colloids, as well as computer simulations, the authors show that tens of thousands of hard spheres compressed under spherical confinement spontaneously crystallize into icosahedral clusters that are entropically favored over the bulk face-centered cubic crystal structure. These findings provide insights into the interplay between confinement and crystn. and into how these are connected to the formation of icosahedral structures.
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    14. 14
      Yu, Y.; Yu, D.; Orme, C. A. Reversible, Tunable, Electric-Field Driven Assembly of Silver Nanocrystal Superlattices. Nano Lett. 2017, 17, 3862– 3869,  DOI: 10.1021/acs.nanolett.7b01323
      14
      Reversible, Tunable, Electric-Field Driven Assembly of Silver Nanocrystal Superlattices
      Yu, Yixuan; Yu, Dian; Orme, Christine A.
      Nano Letters (2017), 17 (6), 3862-3869CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
      Nanocrystal superlattices are typically fabricated by either solvent evapn. or destabilization methods that require long time periods to generate highly ordered structures. In this paper, we report for the first time the use of elec. fields to reversibly drive nanocrystal assembly into superlattices without changing solvent vol. or compn., and show that this method only takes 20 min to produce polyhedral colloidal crystals, which would otherwise need days or weeks. This method offers a way to control the lattice consts. and degree of preferential orientation for superlattices and can suppress the uniaxial superlattice contraction assocd. with solvent evapn. In situ small-angle X-ray scattering expts. indicated that nanocrystal superlattices were formed while solvated, not during drying.
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    15. 15
      Singh, G.; Chan, H.; Baskin, A.; Gelman, E.; Repnin, N.; Kral, P.; Klajn, R. Self-Assembly of Magnetite Nanocubes into Helical Superstructures. Science 2014, 345, 1149– 1153,  DOI: 10.1126/science.1254132
      15
      Self-assembly of magnetite nanocubes into helical superstructures
      Singh, Gurvinder; Chan, Henry; Baskin, Artem; Gelman, Elijah; Repnin, Nikita; Kral, Petr; Klajn, Rafal
      Science (Washington, DC, United States) (2014), 345 (6201), 1149-1153CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
      Organizing inorg. nanocrystals into complex architectures is challenging and typically relies on preexisting templates, such as properly folded DNA or polypeptide chains. We found that under carefully controlled conditions, cubic nanocrystals of magnetite self-assemble into arrays of helical superstructures in a template-free manner with >99% yield. Computer simulations revealed that the formation of helixes is detd. by the interplay of van der Waals and magnetic dipole-dipole interactions, Zeeman coupling, and entropic forces and can be attributed to spontaneous formation of chiral nanocube clusters. Neighboring helixes within their densely packed ensembles tended to adopt the same handedness to maximize packing, thus revealing a novel mechanism of symmetry breaking and chirality amplification.
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    16. 16
      Bishop, K. J.; Wilmer, C. E.; Soh, S.; Grzybowski, B. A. Nanoscale Forces and Their Uses in Self-Assembly. Small 2009, 5, 1600– 1630,  DOI: 10.1002/smll.200900358
      16
      Nanoscale forces and their uses in self-assembly
      Bishop, Kyle J. M.; Wilmer, Christopher E.; Soh, Siowling; Grzybowski, Bartosz A.
      Small (2009), 5 (14), 1600-1630CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)
      A review. The ability to assemble nanoscopic components into larger structures and materials depends crucially on the ability to understand in quant. detail and subsequently "engineer" the interparticle interactions. This Review provides a crit. examn. of the various interparticle forces (van der Waals, electrostatic, magnetic, mol., and entropic) that can be used in nanoscale self-assembly. For each type of interaction, the magnitude and the length scale are discussed, as well as the scaling with particle size and interparticle distance. In all cases, the discussion emphasizes characteristics unique to the nanoscale. These theor. considerations are accompanied by examples of recent exptl. systems, in which specific interaction types were used to drive nanoscopic self-assembly. Overall, this Review aims to provide a comprehensive yet easily accessible resource of nanoscale-specific interparticle forces that can be implemented in models or simulations of self-assembly processes at this scale.
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    17. 17
      Murray, C. B.; Kagan, C. R.; Bawendi, M. G. Self-Organization of CdSe Nanocrystallites into Three-Dimensional Quantum Dot Superlattices. Science 1995, 270, 1335– 1338,  DOI: 10.1126/science.270.5240.1335
      17
      Self-organization of CdSe nanocrystallites into three-dimensional quantum dot superlattices
      Murray, C. B.; Kagan, C. R.; Bawendi, M. G.
      Science (Washington, D. C.) (1995), 270 (5240), 1335-8CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
      The self-organization of CdSe nanocrystallites into three-dimensional semiconductor quantum dot superlattices (colloidal crystals) is demonstrated. The size and spacing of the dots within the superlattice are controlled with near at. precision. This control is a result of synthetic advances that provide CdSe nanocrystallites that are monodisperse within the limit of at. roughness. The methodol. is not limited to semiconductor quantum dots but provides general procedures for the prepn. and characterization of ordered structures of nanocrystallites from a variety of materials.
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    18. 18
      Shevchenko, E. V.; Talapin, D. V.; Kotov, N. A.; O’Brien, S.; Murray, C. B. Structural Diversity in Binary Nanoparticle Superlattices. Nature 2006, 439, 55– 59,  DOI: 10.1038/nature04414
      18
      Structural diversity in binary nanoparticle superlattices
      Shevchenko, Elena V.; Talapin, Dmitri V.; Kotov, Nicholas A.; O'Brien, Stephen; Murray, Christopher B.
      Nature (London, United Kingdom) (2006), 439 (7072), 55-59CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)
      Assembly of small building blocks such as atoms, mols. and nanoparticles into macroscopic structures-i.e., 'bottom up' assembly-is a theme that runs through chem., biol. and material science. Bacteria, macromols. and nanoparticles can self-assemble, generating ordered structures with a precision that challenges current lithog. techniques. The assembly of nanoparticles of two different materials into a binary nanoparticle superlattice (BNSL) can provide a general and inexpensive path to a large variety of materials (metamaterials) with precisely controlled chem. compn. and tight placement of the components. Maximization of the nanoparticle packing d. is proposed as the driving force for BNSL formation, and only a few BNSL structures were predicted to be thermodynamically stable. Recently, colloidal crystals with micrometre-scale lattice spacings were grown from oppositely charged polymethyl methacrylate spheres. Here the authors demonstrate formation of >15 different BNSL structures, using combinations of semiconducting, metallic and magnetic nanoparticle building blocks. At least ten of these colloidal cryst. structures were not reported previously. Elec. charges on sterically stabilized nanoparticles det. BNSL stoichiometry; addnl. contributions from entropic, van der Waals, steric and dipolar forces stabilize the variety of BNSL structures.
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    19. 19
      Boles, M. A.; Talapin, D. V. Many-Body Effects in Nanocrystal Superlattices: Departure from Sphere Packing Explains Stability of Binary Phases. J. Am. Chem. Soc. 2015, 137, 4494– 4502,  DOI: 10.1021/jacs.5b00839
      19
      Many-Body Effects in Nanocrystal Superlattices: Departure from Sphere Packing Explains Stability of Binary Phases
      Boles, Michael A.; Talapin, Dmitri V.
      Journal of the American Chemical Society (2015), 137 (13), 4494-4502CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
      This work analyzes the role of hydrocarbon ligands in the self-assembly of nanocrystal (NC) superlattices. Typical NCs, composed of an inorg. core of radius R and a layer of capping ligands with length L, can be described as soft spheres with softness parameter L/R. Using particle tracking measurements of TEM images, close-packed NCs, like their hard-sphere counterparts, fill space at ∼74% d. independent of softness. The authors uncover deformability of the ligand capping layer that leads to variable effective NC size in response to the coordination environment. This effect plays an important role in the packing of particles in binary nanocrystal superlattices (BNSLs). Measurements on BNSLs composed of NCs of varying softness in several coordination geometries indicate that NCs deform to produce dense BNSLs that would otherwise be low-d. arrangements if the particles remained spherical. Consequently, rationalizing the mixing of 2 NC species during BNSL self-assembly need not employ complex energetic interactions. The authors summarize the anal. in a set of packing rules. These findings contribute to a general understanding of entropic effects during crystn. of deformable objects (e.g., nanoparticles, micelles, globular proteins) that can adapt their shape to the local coordination environment.
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    20. 20
      Coropceanu, I.; Boles, M. A.; Talapin, D. V. Systematic Mapping of Binary Nanocrystal Superlattices: The Role of Topology in Phase Selection. J. Am. Chem. Soc. 2019, 141, 5728– 5740,  DOI: 10.1021/jacs.8b12539
      20
      Systematic Mapping of Binary Nanocrystal Superlattices: The Role of Topology in Phase Selection
      Coropceanu, Igor; Boles, Michael A.; Talapin, Dmitri V.
      Journal of the American Chemical Society (2019), 141 (14), 5728-5740CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
      The self-assembly of two sizes of spherical nanocrystals has revealed a surprisingly diverse library of structures. To date, at least 15 distinct binary nanocrystal superlattice (BNSL) structures have been identified. The stability of these binary phases cannot be fully explained using the traditional conceptual framework treating the assembly process as entropy-driven crystn. of rigid spherical particles. Such deviation from hard sphere behavior may be explained by the soft and deformable layer of ligands that envelops the nanocrystals, which contributes significantly to the overall size and shape of assembling particles. In this work, we describe a set of expts. designed to elucidate the role of the ligand corona in shaping the thermodn. and kinetics of BNSL assembly. Using hydrocarbon-capped Au and PbS nanocrystals as a model binary system, we systematically tuned the core radius (R) and ligand chain length (L) of particles and subsequently assembled them into binary superlattices. The resulting database of binary structures enabled a detailed anal. of the role of effective nanocrystal size ratio, as well as softness expressed as L/R, in directing the assembly of binary structures. This catalog of superlattices allowed us to not only study the frequency of different phases but to also systematically measure the geometric parameters of the BNSLs. This anal. allowed us to evaluate new theor. models treating the cocrystn. of deformable spheres and to formulate new hypotheses about the factors affecting the nucleation and growth of the binary superlattices. Among other insights, our results suggest that the relative abundance of the binary phases obsd. may be explained not only by considerations of thermodn. stability, but also by a postulated preordering of the binary fluid into local structures with icosahedral or polytetrahedral symmetry prior to nucleation.
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    21. 21
      Landman, U.; Luedtke, W. D. Small Is Different: Energetic, Structural, Thermal, and Mechanical Properties of Passivated Nanocluster Assemblies. Faraday Discuss. 2004, 125, 1– 22,  DOI: 10.1039/b312640b
      21
      Small is different: energetic, structural, thermal, and mechanical properties of passivated nanocluster assemblies
      Landman Uzi; Luedtke W D
      Faraday discussions (2004), 125 (), 1-22; discussion 99-116 ISSN:1359-6640.
      We explore, with the use of extensive molecular dynamics simulations, several principal issues pertaining to the energetics of formation of superlattices made through the assembly of passivated nanoclusters, the interactions that underlie the cohesion of such superlattices, and the unique mechanical, thermal and structural properties that they exhibit. Our investigations focus on assemblies made of crystalline gold nanoclusters of variable sizes, passivated by monolayers of alkylthiol molecules. An analytic optimal packing model that correlates in a unified manner several structural characteristics of three-dimensional superlattice assemblies is developed. The model successfully organizes and systematizes a large amount of experimental and simulation data, and it predicts the phase-boundary between different superlattice structural motifs that evolve as a function of the ratio between the chain-length of the extended passivating molecules and the radius of the underlying gold nanocluster. The entropic contribution to the formation free energy of the superlattice assembly is found to be large and of similar magnitude as the potential energy component of the free energy. The major contribution to the cohesive potential energy of the superlattice is shown to originate from van der Waals interactions between molecules that passivate neighboring nanoclusters. The unique mechanical, thermal, thermomechanical, and thermostructural properties of passivated nanocluster assemblies, are discussed.
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    22. 22
      Deng, K.; Luo, Z.; Tan, L.; Quan, Z. Self-Assembly of Anisotropic Nanoparticles into Functional Superstructures. Chem. Soc. Rev. 2020, 49, 6002– 6038,  DOI: 10.1039/D0CS00541J
      22
      Self-assembly of anisotropic nanoparticles into functional superstructures
      Deng, Kerong; Luo, Zhishan; Tan, Li; Quan, Zewei
      Chemical Society Reviews (2020), 49 (16), 6002-6038CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
      A review. Self-assembly of colloidal nanoparticles (NPs) into superstructures offers a flexible and promising pathway to manipulate the nanometer-sized particles and thus make full use of their unique properties. This bottom-up strategy builds a bridge between the NP regime and a new class of transformative materials across multiple length scales for technol. applications. In this field, anisotropic NPs with size- and shape-dependent phys. properties as self-assembly building blocks have long fascinated scientists. Self-assembly of anisotropic NPs not only opens up exciting opportunities to engineer a variety of intriguing and complex superlattice architectures, but also provides access to discover emergent collective properties that stem from their ordered arrangement. Thus, this has stimulated enormous research interests in both fundamental science and technol. applications. This present review comprehensively summarizes the latest advances in this area, and highlights their rich packing behaviors from the viewpoint of NP shape. We provide the basics of the exptl. techniques to produce NP superstructures and structural characterization tools, and detail the delicate assembled structures. Then the current understanding of the assembly dynamics is discussed with the assistance of in situ studies, followed by emergent collective properties from these NP assemblies. Finally, we end this article with the remaining challenges and outlook, hoping to encourage further research in this field.
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    23. 23
      Glotzer, S. C.; Solomon, M. J. Anisotropy of Building Blocks and Their Assembly into Complex Structures. Nat. Mater. 2007, 6, 557– 562,  DOI: 10.1038/nmat1949
      23
      Anisotropy of building blocks and their assembly into complex structures
      Glotzer Sharon C; Solomon Michael J
      Nature materials (2007), 6 (8), 557-62 ISSN:1476-1122.
      A revolution in novel nanoparticles and colloidal building blocks has been enabled by recent breakthroughs in particle synthesis. These new particles are poised to become the 'atoms' and 'molecules' of tomorrow's materials if they can be successfully assembled into useful structures. Here, we discuss the recent progress made in the synthesis of nanocrystals and colloidal particles and draw analogies between these new particulate building blocks and better-studied molecules and supramolecular objects. We argue for a conceptual framework for these new building blocks based on anisotropy attributes and discuss the prognosis for future progress in exploiting anisotropy for materials design and assembly.
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    24. 24
      Millan, J. A.; Ortiz, D.; van Anders, G.; Glotzer, S. C. Self-Assembly of Archimedean Tilings with Enthalpically and Entropically Patchy Polygons. ACS Nano 2014, 8, 2918– 2928,  DOI: 10.1021/nn500147u
      24
      Self-Assembly of Archimedean Tilings with Enthalpically and Entropically Patchy Polygons
      Millan, Jaime A.; Ortiz, Daniel; van Anders, Greg; Glotzer, Sharon C.
      ACS Nano (2014), 8 (3), 2918-2928CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
      Exptl. accessible, rational design rules for the self-assembly of the Archimedean tilings from polygonal nanoplates are presented. The Archimedean tilings represent a model set of target patterns that (i) contain both simple and complex patterns, (ii) are comprised of simple regular shapes, and (iii) contain patterns with potentially interesting materials properties. Via Monte Carlo simulations, the authors propose a set of design rules with general applicability to one- and two-component systems of polygons. These design rules, specified by increasing levels of patchiness, correspond to a reduced set of anisotropy dimensions for robust self-assembly of the Archimedean tilings. The authors show for which tilings entropic patches alone are sufficient for assembly and when short-range enthalpic interactions are required. For the latter, we show how patchy these interactions should be for optimal yield. This study provides a minimal set of guidelines for the design of anisotropic patchy particles that can self-assemble all 11 Archimedean tilings.
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    25. 25
      van Anders, G.; Klotsa, D.; Ahmed, N. K.; Engel, M.; Glotzer, S. C. Understanding Shape Entropy through Local Dense Packing. Proc. Natl. Acad. Sci. U. S. A. 2014, 111, E4812– E4821,  DOI: 10.1073/pnas.1418159111
      25
      Understanding shape entropy through local dense packing
      van Anders, Greg; Klotsa, Daphne; Ahmed, N. Khalid; Engel, Michael; Glotzer, Sharon C.
      Proceedings of the National Academy of Sciences of the United States of America (2014), 111 (45), E4812-E4821CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)
      Entropy drives the phase behavior of colloids ranging from dense suspensions of hard spheres or rods to dil. suspensions of hard spheres and depletants. Entropic ordering of anisotropic shapes into complex crystals, liq. crystals, and even quasicrystals was demonstrated recently in computer simulations and expts. The ordering of shapes appears to arise from the emergence of directional entropic forces (DEFs) that align neighboring particles, but these forces were neither rigorously defined nor quantified in generic systems. Here, the authors show quant. that shape drives the phase behavior of systems of anisotropic particles upon crowding through DEFs. The authors define DEFs in generic systems and compute them for several hard particle systems. The authors show they are on the order of a few times the thermal energy (kBT) at the onset of ordering, placing DEFs on par with traditional depletion, van der Waals, and other intrinsic interactions. In exptl. systems with these other interactions, the authors provide direct quant. evidence that entropic effects of shape also contribute to self-assembly. The authors use DEFs to draw a distinction between self-assembly and packing behavior. The mechanism that generates directional entropic forces is the maximization of entropy by optimizing local particle packing. This mechanism occurs in a wide class of systems and the authors treat, in a unified way, the entropy-driven phase behavior of arbitrary shapes, incorporating the known works of Kirkwood, Onsager, and Asakura and Oosawa.
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    26. 26
      Demortiere, A.; Launois, P.; Goubet, N.; Albouy, P. A.; Petit, C. Shape-Controlled Platinum Nanocubes and Their Assembly into Two-Dimensional and Three-Dimensional Superlattices. J. Phys. Chem. B 2008, 112, 14583– 14592,  DOI: 10.1021/jp802081n
      26
      Shape-Controlled Platinum Nanocubes and Their Assembly into Two-Dimensional and Three-Dimensional Superlattices
      Demortiere, A.; Launois, P.; Goubet, N.; Albouy, P.-A.; Petit, C.
      Journal of Physical Chemistry B (2008), 112 (46), 14583-14592CODEN: JPCBFK; ISSN:1520-6106. (American Chemical Society)
      Liq.-liq. phase transfer was used to synthesize platinum nanocrystals with a cubic morphol. By finely tuning the parameters controlling the nucleation and growth processes, nanometric truncated cubes or perfect cubes may be obtained. This is the 1st time such shapes are obtained with this procedure. The importance of both the length of the capping agent to control the growth process and the bromide anions as poison for the {111} facet is shown. The low degree of size polydispersity allows these nanocrystals to self-assemble with a long-range ordering in two-dimensional and three-dimensional supracrystals. According to the nanocrystal shape, simple cubic or fcc. supracrystals are obsd. It is remarkable to notice that well-faceted supracrystals with sizes ∼10 μm may be obtained.
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    27. 27
      Quan, Z.; Loc, W. S.; Lin, C.; Luo, Z.; Yang, K.; Wang, Y.; Wang, H.; Wang, Z.; Fang, J. Tilted Face-Centered-Cubic Supercrystals of PbS Nanocubes. Nano Lett. 2012, 12, 4409– 4413,  DOI: 10.1021/nl302324b
      27
      Tilted face-centered-cubic supercrystals of PbS nanocubes
      Quan, Zewei; Loc, Welley Siu; Lin, Cuikun; Luo, Zhiping; Yang, Kaikun; Wang, Yuxuan; Wang, Howard; Wang, Zhongwu; Fang, Jiye
      Nano Letters (2012), 12 (8), 4409-4413CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
      We demonstrate a direct fabrication of PbS nanocube supercrystals without size-selection pretreatment on the building blocks. Electron microscopic and synchrotron small angle X-ray scattering analyses confirm that nanocubes pack through a tilted face-centered-cubic (fcc) arrangement, i.e., face-to-face along the 〈110〉super direction, resulting in a real packing efficiency of as high as ∼83%. This new type of superstructure consisting of nanocubes as building blocks, reported here for the first time, is considered the most stable surfactant-capped nanocube superstructure detd. by far.
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    28. 28
      Disch, S.; Wetterskog, E.; Hermann, R. P.; Salazar-Alvarez, G.; Busch, P.; Bruckel, T.; Bergstrom, L.; Kamali, S. Shape Induced Symmetry in Self-Assembled Mesocrystals of Iron Oxide Nanocubes. Nano Lett. 2011, 11, 1651– 1656,  DOI: 10.1021/nl200126v
      28
      Shape Induced Symmetry in Self-Assembled Mesocrystals of Iron Oxide Nanocubes
      Disch, Sabrina; Wetterskog, Erik; Hermann, Raphaeel P.; Salazar-Alvarez, German; Busch, Peter; Brueckel, Thomas; Bergstroem, Lennart; Kamali, Saeed
      Nano Letters (2011), 11 (4), 1651-1656CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
      Grazing incidence small-angle scattering and electron microscopy have been used to show for the first time that nonspherical nanoparticles can assemble into highly ordered body-centered tetragonal mesocrystals. Energy models accounting for the directionality and magnitude of the van der Waals and dipolar interactions as a function of the degree of truncation of the nanocubes illustrated the importance of the directional dipolar forces for the formation of the initial nanocube clusters and the dominance of the van der Waals multibody interactions in the dense packed arrays.
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    29. 29
      Disch, S.; Wetterskog, E.; Hermann, R. P.; Korolkov, D.; Busch, P.; Boesecke, P.; Lyon, O.; Vainio, U.; Salazar-Alvarez, G.; Bergstrom, L.; Bruckel, T. Structural Diversity in Iron Oxide Nanoparticle Assemblies as Directed by Particle Morphology and Orientation. Nanoscale 2013, 5, 3969– 3975,  DOI: 10.1039/c3nr33282a
      29
      Structural diversity in iron oxide nanoparticle assemblies as directed by particle morphology and orientation
      Disch, Sabrina; Wetterskog, Erik; Hermann, Raphael P.; Korolkov, Denis; Busch, Peter; Boesecke, Peter; Lyon, Olivier; Vainio, Ulla; Salazar-Alvarez, German; Bergstroem, Lennart; Brueckel, Thomas
      Nanoscale (2013), 5 (9), 3969-3975CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)
      The mesostructure of ordered arrays of anisotropic nanoparticles is controlled by a combination of packing constraints and interparticle interactions, two factors that are strongly dependent on the particle morphol. We have investigated how the degree of truncation of iron oxide nanocubes controls the mesostructure and particle orientation in drop cast mesocrystal arrays. The combination of grazing incidence small-angle X-ray scattering and SEM shows that mesocrystals of highly truncated cubic nanoparticles assemble in an fcc-type mesostructure, similar to arrays formed by iron oxide nanospheres, but with a significantly reduced packing d. and displaying two different growth orientations. Strong satellite reflections in the GISAXS pattern indicate a commensurate mesoscopic superstructure that is related to stacking faults in mesocrystals of the anisotropic nanocubes. Our results show how subtle variation in shape anisotropy can induce oriented arrangements of nanoparticles of different structures and also create mesoscopic superstructures of larger periodicity.
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    30. 30
      Sanchez-Iglesias, A.; Grzelczak, M.; Perez-Juste, J.; Liz-Marzan, L. M. Binary Self-Assembly of Gold Nanowires with Nanospheres and Nanorods. Angew. Chem., Int. Ed. Engl. 2010, 49, 9985– 9989,  DOI: 10.1002/anie.201005891
      30
      Binary self-assembly of gold nanowires with nanospheres and nanorods
      Sanchez-Iglesias Ana; Grzelczak Marek; Perez-Juste Jorge; Liz-Marzan Luis M
      Angewandte Chemie (International ed. in English) (2010), 49 (51), 9985-9 ISSN:.
      There is no expanded citation for this reference.
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    31. 31
      Paik, T.; Ko, D. K.; Gordon, T. R.; Doan-Nguyen, V.; Murray, C. B. Studies of Liquid Crystalline Self-Assembly of GdF3 Nanoplates by In-Plane, Out-of-Plane SAXS. ACS Nano 2011, 5, 8322– 8330,  DOI: 10.1021/nn203049t
      31
      Studies of Liquid Crystalline Self-Assembly of GdF3 Nanoplates by In-Plane, Out-of-Plane SAXS
      Paik, Taejong; Ko, Dong-Kyun; Gordon, Thomas R.; Doan-Nguyen, Vicky; Murray, Christopher B.
      ACS Nano (2011), 5 (10), 8322-8330CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
      Directed self-assembly of colloidal nanocrystals into ordered superlattices enables the prepn. of novel metamaterials with diverse functionalities. Structural control and precise characterization of these superlattices allow the interactions between individual nanocrystal building blocks and the origin of their collective properties to be understood. Here, the authors report the directed liq. interfacial assembly of gadolinium trifluoride (GdF3) nanoplates into liq. cryst. assemblies displaying long-range orientational and positional order. The macroscopic orientation of superlattices is controlled by changing the subphases upon which liq. interfacial assembly occurs. The assembled structures are characterized by a combination of TEM and small-angle x-ray scattering (SAXS) measurements performed on a lab. diffractometer. By doping GdF3 nanoplates with europium (Eu3+), luminescent phosphorescent superlattices with controlled structure are produced and enable detailed structural and optical characterization.
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    32. 32
      Nagaoka, Y.; Wang, T.; Lynch, J.; LaMontagne, D.; Cao, Y. C. Binary Assembly of Colloidal Semiconductor Nanorods with Spherical Metal Nanoparticles. Small 2012, 8, 843– 846,  DOI: 10.1002/smll.201101902
      32
      Binary Assembly of Colloidal Semiconductor Nanorods with Spherical Metal Nanoparticles
      Nagaoka, Yasutaka; Wang, Tie; Lynch, Jared; LaMontagne, Derek; Cao, Y. Charles
      Small (2012), 8 (6), 843-846CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)
      To explore the possibility of overcoming entropically and energetically unfavorable interactions which is crit. for the formation of binary assemblies of colloidal nanorods with nanospheres, we used colloidal CdSe/CdS semiconductor nanorods and spherical gold nanoparticles as a model system. Using literature methods, the authors synthesized octadecylphosphonate-functionalized CdSe/CdS nanorods and dodecanethiol (DDT)-capped gold nanoparticles. Since gold exhibits a very large Hamaker const., we originally hypothesized that the strong van der Waals (vdW) attraction between CdSe/CdS nanorods and gold nanoparticles would prevent the phase sepn. of these two building blocks. However, our exptl. results show that the use of triphenylphosphine (TPP) as an additive is important to the formation of binary assemblies of CdSe/CdS nanorods with gold nanoparticles. The results from our mechanistic studies suggest that the formation of these binary assemblies is a kinetically limited process, in which suitable additives and spherical nanoparticles with a high dielec. const. and a large Hamaker const. play important roles.
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    33. 33
      Ye, X.; Millan, J. A.; Engel, M.; Chen, J.; Diroll, B. T.; Glotzer, S. C.; Murray, C. B. Shape Alloys of Nanorods and Nanospheres from Self-Assembly. Nano Lett. 2013, 13, 4980– 4988,  DOI: 10.1021/nl403149u
      33
      Shape Alloys of Nanorods and Nanospheres from Self-Assembly
      Ye, Xingchen; Millan, Jaime A.; Engel, Michael; Chen, Jun; Diroll, Benjamin T.; Glotzer, Sharon C.; Murray, Christopher B.
      Nano Letters (2013), 13 (10), 4980-4988CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
      Mixts. of anisotropic nanocrystals promise a great diversity of superlattices and phase behaviors beyond those of single-component systems. However, obtaining a colloidal shape alloy in which two different shapes are thermodynamically co-assembled into a cryst. superlattice has remained a challenge. The authors present a joint exptl.-computational investigation of two geometrically ubiquitous nanocryst. building blocks - nanorods and nanospheres - that overcome their natural entropic tendency toward macroscopic phase sepn. and co-assemble into three intriguing phases over centimeter scales, including an AB2-type binary superlattice. Monte Carlo simulations reveal that, although this shape alloy is entropically stable at high packing fraction, demixing is favored at exptl. densities. Simulations with short-ranged attractive interactions demonstrate that the alloy is stabilized by interactions induced by ligand stabilizers and/or depletion effects. An asymmetry in the relative interaction strength between rods and spheres improves the robustness of the self-assembly process.
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    34. 34
      Ming, T.; Kou, X.; Chen, H.; Wang, T.; Tam, H. L.; Cheah, K. W.; Chen, J. Y.; Wang, J. Ordered Gold Nanostructure Assemblies Formed by Droplet Evaporation. Angew. Chem., Int. Ed. Engl. 2008, 47, 9685– 9690,  DOI: 10.1002/anie.200803642
      34
      Ordered gold nanostructure assemblies formed by droplet evaporation
      Ming Tian; Kou Xiaoshan; Chen Huanjun; Wang Tao; Tam Hoi-Lam; Cheah Kok-Wai; Chen Ji-Yao; Wang Jianfang
      Angewandte Chemie (International ed. in English) (2008), 47 (50), 9685-90 ISSN:.
      There is no expanded citation for this reference.
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    35. 35
      Castelli, A.; de Graaf, J.; Prato, M.; Manna, L.; Arciniegas, M. P. Tic-Tac-Toe Binary Lattices from the Interfacial Self-Assembly of Branched and Spherical Nanocrystals. ACS Nano 2016, 10, 4345– 4353,  DOI: 10.1021/acsnano.5b08018
      35
      Tic-Tac-Toe Binary Lattices from the Interfacial Self-Assembly of Branched and Spherical Nanocrystals
      Castelli, Andrea; de Graaf, Joost; Prato, Mirko; Manna, Liberato; Arciniegas, Milena P.
      ACS Nano (2016), 10 (4), 4345-4353CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
      The self-organization of nanocrystals has proven to be a versatile route to achieve increasingly sophisticated structures of materials, where the shape and properties of individual particles impact the final functionalities. Recent works have addressed this topic by combining various shapes to achieve more complex arrangements of particles than are possible in single-component samples. However, the ability to create intricate architectures over large regions by exploiting the shape of multiply branched nanocrystals to host a second component remains unexplored. Here, we show how the concave shape of a branched nanocrystal, the so-called octapod, is able to anchor a sphere. The two components self-assemble into a locally ordered monolayer consisting of an intercalated square lattice of octapods and spheres, which is reminiscent of the "tic-tac-toe" game. These tic-tac-toe domains form through an interfacial self-assembly that occurs by the dewetting of a hexane layer contg. both particle types. By varying the exptl. conditions and performing mol. dynamics simulations, we show that the ligands coating the octapods are crucial to the formation of this structure. We find that the tendency of an octapod to form an interlocking-type structure with a second octapod strongly depends on the ligand shell of the pods. Breaking this tendency by ligand exchange allows the octapods to assemble into a more relaxed configuration, which is able to form a lock-and-key-type structure with a sphere, when they have a suitable size ratio. Our findings provide an example of a more versatile use of branched nanocrystals in self-assembled functional materials.
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    36. 36
      Paik, T.; Murray, C. B. Shape-Directed Binary Assembly of Anisotropic Nanoplates: A Nanocrystal Puzzle with Shape-Complementary Building Blocks. Nano Lett. 2013, 13, 2952– 2956,  DOI: 10.1021/nl401370n
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      Shape-Directed Binary Assembly of Anisotropic Nanoplates: A Nanocrystal Puzzle with Shape-Complementary Building Blocks
      Paik, Taejong; Murray, Christopher B.
      Nano Letters (2013), 13 (6), 2952-2956CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
      The authors present the binary self-assembly of two anisotropic nanoplate building blocks mediated by shape complementarity. The authors use rhombic GdF3 and tripodal Gd2O3 nanoplates as building blocks in which the size and shape are designed to be optimal for complementary organization. A liq. interfacial assembly technique gave self-assembled binary superlattices from two anisotropic nanoplates over a micrometer length scale. Shape-directed self-assembly guides the position of each anisotropic nanoplate in the binary superlattices, allowing for long-range orientational and positional order of each building block. The design of shape complementary anisotropic building blocks offers the possibility to self-assemble binary superlattices with predictable and designable structures.
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    37. 37
      Paik, T.; Diroll, B. T.; Kagan, C. R.; Murray, C. B. Binary and Ternary Superlattices Self-Assembled from Colloidal Nanodisks and Nanorods. J. Am. Chem. Soc. 2015, 137, 6662– 6669,  DOI: 10.1021/jacs.5b03234
      37
      Binary and Ternary Superlattices Self-Assembled from Colloidal Nanodisks and Nanorods
      Paik, Taejong; Diroll, Benjamin T.; Kagan, Cherie R.; Murray, Christopher B.
      Journal of the American Chemical Society (2015), 137 (20), 6662-6669CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
      The formation of binary and ternary superlattices from colloidal two-dimensional LaF3 nanodisks and one-dimensional CdSe/CdS nanorods was achieved via liq. interfacial assembly. The colloidal nanodisks and nanorods are coassembled into AB-, AB2-, and AB6-type binary arrays detd. by their relative size ratio and concn. to maximize their packing d. The position and orientation of anisotropic nanocrystal building blocks are tightly controlled in the self-assembled binary and ternary lattices. The macroscopic orientation of the superlattices is further tuned by changing the liq. subphase used for self-assembly, resulting in the formation of lamellar-type binary liq. cryst. superlattices. A ternary superlattice was self-assembled from two different sizes of nanodisks and a nanorod, which offers the unique opportunity to design multifunctional metamaterials.
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    38. 38
      Elbert, K. C.; Zygmunt, W.; Vo, T.; Vara, C. M.; Rosen, D. J.; Krook, N. M.; Glotzer, S. C.; Murray, C. B. Anisotropic Nanocrystal Shape and Ligand Design for Co-Assembly. Sci. Adv. 2021, 7, eabf9402  DOI: 10.1126/sciadv.abf9402
      There is no corresponding record for this reference.
    39. 39
      Protesescu, L.; Yakunin, S.; Bodnarchuk, M. I.; Krieg, F.; Caputo, R.; Hendon, C. H.; Yang, R. X.; Walsh, A.; Kovalenko, M. V. Nanocrystals of Cesium Lead Halide Perovskites (CsPbX3, X = Cl, Br, and I): Novel Optoelectronic Materials Showing Bright Emission with Wide Color Gamut. Nano Lett. 2015, 15, 3692– 3696,  DOI: 10.1021/nl5048779
      39
      Nanocrystals of Cesium Lead Halide Perovskites (CsPbX3, X = Cl, Br, and I): Novel Optoelectronic Materials Showing Bright Emission with Wide Color Gamut
      Protesescu, Loredana; Yakunin, Sergii; Bodnarchuk, Maryna I.; Krieg, Franziska; Caputo, Riccarda; Hendon, Christopher H.; Yang, Ruo Xi; Walsh, Aron; Kovalenko, Maksym V.
      Nano Letters (2015), 15 (6), 3692-3696CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
      Metal halides perovskites, such as hybrid org.-inorg. MeNH3PbI3, are newcomer optoelectronic materials that have attracted enormous attention as soln.-deposited absorbing layers in solar cells with power conversion efficiencies reaching 20%. A new avenue for halide perovskites was demonstrated by designing highly luminescent perovskite-based colloidal quantum dot materials. Monodisperse colloidal nanocubes (4-15 nm edge lengths) of fully inorg. perovskites (CsPbX3, X = Cl, Br, and I or mixed halide systems Cl/Br and Br/I) were synthesized using inexpensive com. precursors. Through compositional modulations and quantum size-effects, the bandgap energies and emission spectra are readily tunable over the entire visible spectral region of 410-700 nm. The luminescence of CsPbX3 nanocrystals is characterized by narrow emission line-widths of 12-42 nm, wide color gamut covering up to 140% of the NTSC color std., high quantum yields of ≤90%, and radiative lifetimes at 1-29 ns. The compelling combination of enhanced optical properties and chem. robustness makes CsPbX3 nanocrystals appealing for optoelectronic applications, particularly for blue and green spectral regions (410-530 nm), where typical metal chalcogenide-based quantum dots suffer from photodegrdn.
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    40. 40
      Kovalenko, M. V.; Protesescu, L.; Bodnarchuk, M. I. Properties and Potential Optoelectronic Applications of Lead Halide Perovskite Nanocrystals. Science 2017, 358, 745– 750,  DOI: 10.1126/science.aam7093
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      Properties and potential optoelectronic applications of lead halide perovskite nanocrystals
      Kovalenko, Maksym V.; Protesescu, Loredana; Bodnarchuk, Maryna I.
      Science (Washington, DC, United States) (2017), 358 (6364), 745-750CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
      A review. Semiconducting lead halide perovskites (LHPs) have not only become prominent thin-film absorber materials in photovoltaics but have also proven to be disruptive in the field of colloidal semiconductor nanocrystals (NCs). The most important feature of LHP NCs is their so-called defect-tolerance-the apparently benign nature of structural defects, highly abundant in these compds., with respect to optical and electronic properties. Here, we review the important differences that exist in the chem. and physics of LHP NCs as compared with more conventional, tetrahedrally bonded, elemental, and binary semiconductor NCs (such as silicon, germanium, cadmium selenide, gallium arsenide, and indium phosphide). We survey the prospects of LHP NCs for optoelectronic applications such as in television displays, light-emitting devices, and solar cells, emphasizing the practical hurdles that remain to be overcome.
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    41. 41
      Akkerman, Q. A.; Rainò, G.; Kovalenko, M. V.; Manna, L. Genesis, Challenges and Opportunities for Colloidal Lead Halide Perovskite Nanocrystals. Nat. Mater. 2018, 17, 394– 405,  DOI: 10.1038/s41563-018-0018-4
      41
      Genesis, challenges and opportunities for colloidal lead halide perovskite nanocrystals
      Akkerman, Quinten A.; Raino, Gabriele; Kovalenko, Maksym V.; Manna, Liberato
      Nature Materials (2018), 17 (5), 394-405CODEN: NMAACR; ISSN:1476-1122. (Nature Research)
      A review. Lead halide perovskites (LHPs) in the form of nanometer-sized colloidal crystals, or nanocrystals (NCs), have attracted the attention of diverse materials scientists due to their unique optical versatility, high photoluminescence quantum yields and facile synthesis. LHP NCs have a 'soft' and predominantly ionic lattice, and their optical and electronic properties are highly tolerant to structural defects and surface states. Therefore, they cannot be approached with the same exptl. mindset and theor. framework as conventional semiconductor NCs. In this Review, we discuss LHP NCs historical and current research pursuits, challenges in applications, and the related present and future mitigation strategies explored.
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      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXltFOrsrw%253D&md5=33285d81190915543b01d5ddb47c2e8b
    42. 42
      Dey, A.; Ye, J.; De, A.; Debroye, E.; Ha, S. K.; Bladt, E.; Kshirsagar, A. S.; Wang, Z.; Yin, J.; Wang, Y.; Quan, L. N.; Yan, F.; Gao, M.; Li, X.; Shamsi, J.; Debnath, T.; Cao, M.; Scheel, M. A.; Kumar, S.; Steele, J. A.; Gerhard, M.; Chouhan, L.; Xu, K.; Wu, X. G.; Li, Y.; Zhang, Y.; Dutta, A.; Han, C.; Vincon, I.; Rogach, A. L.; Nag, A.; Samanta, A.; Korgel, B. A.; Shih, C. J.; Gamelin, D. R.; Son, D. H.; Zeng, H.; Zhong, H.; Sun, H.; Demir, H. V.; Scheblykin, I. G.; Mora-Sero, I.; Stolarczyk, J. K.; Zhang, J. Z.; Feldmann, J.; Hofkens, J.; Luther, J. M.; Perez-Prieto, J.; Li, L.; Manna, L.; Bodnarchuk, M. I.; Kovalenko, M. V.; Roeffaers, M. B. J.; Pradhan, N.; Mohammed, O. F.; Bakr, O. M.; Yang, P.; Muller-Buschbaum, P.; Kamat, P. V.; Bao, Q.; Zhang, Q.; Krahne, R.; Galian, R. E.; Stranks, S. D.; Bals, S.; Biju, V.; Tisdale, W. A.; Yan, Y.; Hoye, R. L. Z.; Polavarapu, L. State of the Art and Prospects for Halide Perovskite Nanocrystals. ACS Nano 2021, 15, 10775– 10981,  DOI: 10.1021/acsnano.0c08903
      42
      State of the Art and Prospects for Halide Perovskite Nanocrystals
      Dey, Amrita; Ye, Junzhi; De, Apurba; Debroye, Elke; Ha, Seung Kyun; Bladt, Eva; Kshirsagar, Anuraj S.; Wang, Ziyu; Yin, Jun; Wang, Yue; Quan, Li Na; Yan, Fei; Gao, Mengyu; Li, Xiaoming; Shamsi, Javad; Debnath, Tushar; Cao, Muhan; Scheel, Manuel A.; Kumar, Sudhir; Steele, Julian A.; Gerhard, Marina; Chouhan, Lata; Xu, Ke; Wu, Xian-gang; Li, Yanxiu; Zhang, Yangning; Dutta, Anirban; Han, Chuang; Vincon, Ilka; Rogach, Andrey L.; Nag, Angshuman; Samanta, Anunay; Korgel, Brian A.; Shih, Chih-Jen; Gamelin, Daniel R.; Son, Dong Hee; Zeng, Haibo; Zhong, Haizheng; Sun, Handong; Demir, Hilmi Volkan; Scheblykin, Ivan G.; Mora-Sero, Ivan; Stolarczyk, Jacek K.; Zhang, Jin Z.; Feldmann, Jochen; Hofkens, Johan; Luther, Joseph M.; Perez-Prieto, Julia; Li, Liang; Manna, Liberato; Bodnarchuk, Maryna I.; Kovalenko, Maksym V.; Roeffaers, Maarten B. J.; Pradhan, Narayan; Mohammed, Omar F.; Bakr, Osman M.; Yang, Peidong; Mueller-Buschbaum, Peter; Kamat, Prashant V.; Bao, Qialiang; Zhang, Qiao; Krahne, Roman; Galian, Raquel E.; Stranks, Samuel D.; Bals, Sara; Biju, Vasudevanpillai; Tisdale, William A.; Yan, Yong; Hoye, Robert L. Z.; Polavarapu, Lakshminarayana
      ACS Nano (2021), 15 (7), 10775-10981CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
      A review. Metal-halide perovskites have rapidly emerged as one of the most promising materials of the 21st century, with many exciting properties and great potential for a broad range of applications, from photovoltaics to optoelectronics and photocatalysis. The ease with which metal-halide perovskites can be synthesized in the form of brightly luminescent colloidal nanocrystals, as well as their tunable and intriguing optical and electronic properties, has attracted researchers from different disciplines of science and technol. In the last few years, there has been a significant progress in the shape-controlled synthesis of perovskite nanocrystals and understanding of their properties and applications. In this comprehensive review, researchers having expertise in different fields (chem., physics, and device engineering) of metal-halide perovskite nanocrystals have joined together to provide a state of the art overview and future prospects of metal-halide perovskite nanocrystal research.
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    43. 43
      Lu, M.; Zhang, Y.; Wang, S.; Guo, J.; Yu, W. W.; Rogach, A. L. Metal Halide Perovskite Light-Emitting Devices: Promising Technology for Next-Generation Displays. Adv. Funct. Mater. 2019, 29, 1902008,  DOI: 10.1002/adfm.201902008
      There is no corresponding record for this reference.
    44. 44
      Quan, L. N.; Rand, B. P.; Friend, R. H.; Mhaisalkar, S. G.; Lee, T. W.; Sargent, E. H. Perovskites for Next-Generation Optical Sources. Chem. Rev. 2019, 119, 7444– 7477,  DOI: 10.1021/acs.chemrev.9b00107
      44
      Perovskites for Next-Generation Optical Sources
      Quan, Li Na; Rand, Barry P.; Friend, Richard H.; Mhaisalkar, Subodh Gautam; Lee, Tae-Woo; Sargent, Edward H.
      Chemical Reviews (Washington, DC, United States) (2019), 119 (12), 7444-7477CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
      Next-generation displays and lighting technologies require efficient optical sources that combine brightness, color purity, stability, substrate flexibility. Metal halide perovskites have potential use in a wide range of applications, for they possess excellent charge transport, bandgap tunability and, in the most promising recent optical source materials, intense and efficient luminescence. This review links metal halide perovskites' performance as efficient light emitters with their underlying materials electronic and photophys. attributes.
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    45. 45
      Utzat, H.; Sun, W.; Kaplan, A. E. K.; Krieg, F.; Ginterseder, M.; Spokoyny, B.; Klein, N. D.; Shulenberger, K. E.; Perkinson, C. F.; Kovalenko, M. V.; Bawendi, M. G. Coherent Single-Photon Emission From Colloidal Lead Halide Perovskite Quantum Dots. Science 2019, 363, 1068– 1072,  DOI: 10.1126/science.aau7392
      45
      Coherent single-photon emission from colloidal lead halide perovskite quantum dots
      Utzat, Hendrik; Sun, Weiwei; Kaplan, Alexander E. K.; Krieg, Franziska; Ginterseder, Matthias; Spokoyny, Boris; Klein, Nathan D.; Shulenberger, Katherine E.; Perkinson, Collin F.; Kovalenko, Maksym V.; Bawendi, Moungi G.
      Science (Washington, DC, United States) (2019), 363 (6431), 1068-1072CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
      Chem. made colloidal semiconductor quantum dots have long been proposed as scalable and color-tunable single emitters in quantum optics, but they have typically suffered from prohibitively incoherent emission. The authors now demonstrate that individual colloidal lead halide perovskite quantum dots (PQDs) display highly efficient single-photon emission with optical coherence times as long as 80 ps, an appreciable fraction of their 210-ps radiative lifetimes. These measurements suggest that PQDs should be explored as building blocks in sources of indistinguishable single photons and entangled photon pairs. Their results present a starting point for the rational design of lead halide perovskite-based quantum emitters that have fast emission, wide spectral tunability, and scalable prodn. and that benefit from the hybrid integration with nanophotonic components that has been demonstrated for colloidal materials.
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    46. 46
      Raino, G.; Nedelcu, G.; Protesescu, L.; Bodnarchuk, M. I.; Kovalenko, M. V.; Mahrt, R. F.; Stoferle, T. Single Cesium Lead Halide Perovskite Nanocrystals at Low Temperature: Fast Single-Photon Emission, Reduced Blinking, and Exciton Fine Structure. ACS Nano 2016, 10, 2485– 2490,  DOI: 10.1021/acsnano.5b07328
      46
      Single Cesium Lead Halide Perovskite Nanocrystals at Low Temperature: Fast Single-Photon Emission, Reduced Blinking, and Exciton Fine Structure
      Raino, Gabriele; Nedelcu, Georgian; Protesescu, Loredana; Bodnarchuk, Maryna I.; Kovalenko, Maksym V.; Mahrt, Rainer F.; Stoferle, Thilo
      ACS Nano (2016), 10 (2), 2485-2490CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
      At low temp. single colloidal CsPbX3 (X = Cl/Br) nanocrystals exhibit stable, narrow-band emission with suppressed blinking and small spectral diffusion. Photon antibunching demonstrates unambiguously nonclassical single-photon emission with radiative decay ∼250 ps, representing a significant acceleration compared to other common quantum emitters. High-resoln. spectroscopy provides insight into the complex nature of the emission process such as the fine structure and charged exciton dynamics.
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    47. 47
      Almeida, G.; Goldoni, L.; Akkerman, Q.; Dang, Z.; Khan, A. H.; Marras, S.; Moreels, I.; Manna, L. Role of Acid-Base Equilibria in the Size, Shape, and Phase Control of Cesium Lead Bromide Nanocrystals. ACS Nano 2018, 12, 1704– 1711,  DOI: 10.1021/acsnano.7b08357
      47
      Role of Acid-Base Equilibria in the Size, Shape, and Phase Control of Cesium Lead Bromide Nanocrystals
      Almeida, Guilherme; Goldoni, Luca; Akkerman, Quinten; Dang, Zhiya; Khan, Ali Hossain; Marras, Sergio; Moreels, Iwan; Manna, Liberato
      ACS Nano (2018), 12 (2), 1704-1711CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
      A binary ligand system composed of aliph. carboxylic acids and primary amines of various chain lengths is commonly employed in diverse synthesis methods for CsPbBr3 nanocrystals (NCs). The authors have carried out a systematic study examg. how the concn. of ligands (oleylamine and oleic acid) and the resulting acidity (or basicity) affects the hot-injection synthesis of CsPbBr3 NCs. The authors devise a general synthesis scheme for cesium lead bromide NCs which allows control over size, size distribution, shape, and phase (CsPbBr3 or Cs4PbBr6) by combining key insights on the acid-base interactions that rule this ligand system. Also, the authors' findings shed light upon the soly. of PbBr2 in this binary ligand system, and plausible mechanisms are suggested to understand the ligand-mediated phase control and structural stability of CsPbBr3 NCs.
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    48. 48
      Hudait, B.; Dutta, S. K.; Patra, A.; Nasipuri, D.; Pradhan, N. Facets Directed Connecting Perovskite Nanocrystals. J. Am. Chem. Soc. 2020, 142, 7207– 7217,  DOI: 10.1021/jacs.0c02168
      48
      Facets Directed Connecting Perovskite Nanocrystals
      Hudait, Biswajit; Dutta, Sumit Kumar; Patra, Avijit; Nasipuri, Diptam; Pradhan, Narayan
      Journal of the American Chemical Society (2020), 142 (15), 7207-7217CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
      Connecting nanocrystals with removal of interface ligand barriers is one of the key steps for efficient carrier transportation in optoelectronic device fabrication. Typically, ion migration for crystal deformation or connection with other nanocrystals needs a solvent as medium. However, on the contrary, this has been obsd. for CsPbBr3 perovskite nanocrystals in film where nanocrystals were swollen to get wider and fused with adjacent nanocrystals in self-assembly on film during solvent evapn. Depending on precursor compn. and exposed facets, again these connections could be programmed for tuning their connecting directions leading to different shapes. Aging further on solid substrate, these were also turned to continuous film of nanostructures eliminating all interparticle gaps on the film. This transformation could be ceased at any point of time, simply by heating or adding sufficient ligands. Anal. suggested that these unique and controlled connections were only obsd. with polyhedron shaped nanostructures with certain compns. and not with traditionally cubes. Details of this solid-surface transformation during solvent evapn. were analyzed, and an interparticle material transfer type mechanism was proposed. As these observations were not seen in chalcogenide and oxide nanocrystals and exclusively obsd. in perovskite nanocrystals, this would add new fundamentals to the insights of crystal growths of nanocrystals and would also help in obtaining films of connecting nanocrystals.
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    49. 49
      Bera, S.; Behera, R. K.; Pradhan, N. alpha-Halo Ketone for Polyhedral Perovskite Nanocrystals: Evolutions, Shape Conversions, Ligand Chemistry, and Self-Assembly. J. Am. Chem. Soc. 2020, 142, 20865– 20874,  DOI: 10.1021/jacs.0c10688
      49
      α-Halo Ketone for Polyhedral Perovskite Nanocrystals: Evolutions, Shape Conversions, Ligand Chemistry, and Self-Assembly
      Bera, Suman; Behera, Rakesh Kumar; Pradhan, Narayan
      Journal of the American Chemical Society (2020), 142 (49), 20865-20874CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
      Bright lead halide perovskite nanocrystals, which have been extensively studied in the past 5 years, are mostly confined to a six faceted hexahedron (cube/platelet) shape. With variations of ligand, precursor, reaction temp., and surface modification, their brightness has been enhanced and phase became stable, but ultimate nanocrystals still retained the hexahedron cube or platelet shape in most of the hot injection reactions. In contrast, by exploration of α-halo ketone in amine as a halide precursor, different shaped nanocrystals without compromising the photoluminescence quantum yield (PLQY) are reported. Confining to orthorhombic CsPbBr3, the obtained nanocrystals are stabilized by 12 facets ({200}, {020}, {112}) and led to 12 faceted rhombic dodecahedrons. These facets are absolutely different from six ({110}, {002}) equiv. facets of widely reported orthorhombic cube shaped CsPbBr3 nanocrystals. These also retained the colloidal and phase stability, as well as showed near unity PLQY. With further annealing, these are transformed to 26 faceted rhombicuboctahedrons by dissolving all their vertices. Importantly, these 12 faceted nanocrystals showed wide area self-assembly in most of the reactions. It has also been concluded that primary ammonium ions led to six faceted nanocrystals, but tertiary ammonium ions obtained in this case stabilized different group of facets. While perovskite nanocrystals were broadly confined to only nanocubes, these new nanocrystals with intense emission would certainly provide a new avenue for continuing their further research.
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    50. 50
      Kovalenko, M. V.; Bodnarchuk, M. I. Lead Halide Perovskite Nanocrystals: From Discovery to Self-Assembly and Applications. Chimia 2017, 71, 461– 470,  DOI: 10.2533/chimia.2017.461
      50
      Lead halide perovskite nanocrystals: from discovery to self-assembly and applications
      Kovalenko, Maksym V.; Bodnarchuk, Maryna I.
      Chimia (2017), 71 (7-8), 461-470CODEN: CHIMAD ISSN:. (Swiss Chemical Society)
      A review. Lead halide perovskites (LHPs) of the general formula APbX3 (A=Cs+, CH3NH3+, or CH(NH2)2+; X=Cl, Br, or I) have recently emerged as a unique class of low-cost, versatile semiconductors of high optoelectronic quality. These materials offer exceptionally facile soln.-based engineerability in the form of bulk single crystals, thin films, or supported and unsupported nanostructures. The lattermost form, esp. as colloidal nanocrystals (NCs), holds great promise as a versatile photonic source, operated via bright photoluminescence (PL) in displays or lighting (energy down-conversion of blue light into green and red), or via electroluminescence in light-emitting diodes. In this article we discuss the recent history of the development of highly-luminescent NCs of LHPs, the current state-of-the-art of this class of materials, and the future prospects of this highly active research field. We also report the demonstration of long-range ordered, self-organized superlattice structures obtained from cubeshaped colloidal CsPbBr3 NCs using drying-mediated self-assembly.
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    51. 51
      Nagaoka, Y.; Hills-Kimball, K.; Tan, R.; Li, R.; Wang, Z.; Chen, O. Nanocube Superlattices of Cesium Lead Bromide Perovskites and Pressure-Induced Phase Transformations at Atomic and Mesoscale Levels. Adv. Mater. 2017, 29, 1606666,  DOI: 10.1002/adma.201606666
      There is no corresponding record for this reference.
    52. 52
      van der Burgt, J. S.; Geuchies, J. J.; van der Meer, B.; Vanrompay, H.; Zanaga, D.; Zhang, Y.; Albrecht, W.; Petukhov, A. V.; Filion, L.; Bals, S.; Swart, I.; Vanmaekelbergh, D. Cuboidal Supraparticles Self-Assembled from Cubic CsPbBr3 Perovskite Nanocrystals. J. Phys. Chem. C 2018, 122, 15706– 15712,  DOI: 10.1021/acs.jpcc.8b02699
      52
      Cuboidal Supraparticles Self-Assembled from Cubic CsPbBr3 Perovskite Nanocrystals
      van der Burgt, Julia S.; Geuchies, Jaco J.; van der Meer, Berend; Vanrompay, Hans; Zanaga, Daniele; Zhang, Yang; Albrecht, Wiebke; Petukhov, Andrei V.; Filion, Laura; Bals, Sara; Swart, Ingmar; Vanmaekelbergh, Daniel
      Journal of Physical Chemistry C (2018), 122 (27), 15706-15712CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)
      Colloidal CsPbBr3 nanocrystals (NCs) have emerged as promising candidates for various opto-electronic applications, such as light-emitting diodes, photodetectors, and solar cells. Here, we report on the self-assembly of cubic NCs from an org. suspension into ordered cuboidal supraparticles (SPs) and their structural and optical properties. Upon increasing the NC concn. or by addn. of a nonsolvent, the formation of the SPs occurs homogeneously in the suspension, as monitored by in situ X-ray scattering measurements. The three-dimensional structure of the SPs was resolved through high-angle annular dark-field scanning transmission electron microscopy and electron tomog. The NCs are atomically aligned but not connected. We characterize NC vacancies on superlattice positions both in the bulk and on the surface of the SPs. The occurrence of localized at.-type NC vacancies-instead of delocalized ones-indicates that NC-NC attractions are important in the assembly, as we verify with Monte Carlo simulations. Even when assembled in SPs, the NCs show bright emission, with a red shift of about 30 meV compared to NCs in suspension.
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    53. 53
      Rainò, G.; Becker, M. A.; Bodnarchuk, M. I.; Mahrt, R. F.; Kovalenko, M. V.; Stöferle, T. Superfluorescence From Lead Halide Perovskite Quantum Dot Superlattices. Nature 2018, 563, 671– 675,  DOI: 10.1038/s41586-018-0683-0
      53
      Superfluorescence from lead halide perovskite quantum dot superlattices
      Raino, Gabriele; Becker, Michael A.; Bodnarchuk, Maryna I.; Mahrt, Rainer F.; Kovalenko, Maksym V.; Stoferle, Thilo
      Nature (London, United Kingdom) (2018), 563 (7733), 671-675CODEN: NATUAS; ISSN:0028-0836. (Nature Research)
      An ensemble of emitters can behave very differently from its individual constituents when they interact coherently via a common light field. After excitation of such an ensemble, collective coupling can give rise to a many-body quantum phenomenon that results in short, intense bursts of light-so-called superfluorescence1. Because this phenomenon requires a fine balance of interactions between the emitters and their decoupling from the environment, together with close identity of the individual emitters, superfluorescence has thus far been obsd. only in a limited no. of systems, such as certain at. and mol. gases and a few solid-state systems2-7. The generation of superfluorescent light in colloidal nanocrystals (which are bright photonic sources practically suited for optoelectronics8,9) has been precluded by inhomogeneous emission broadening, low oscillator strength, and fast exciton dephasing. Here we show that cesium lead halide (CsPbX3, X = Cl, Br) perovskite nanocrystals10-13 that are self-organized into highly ordered three-dimensional superlattices exhibit key signatures of superfluorescence. These are dynamically red-shifted emission with more than 20-fold accelerated radiative decay, extension of the first-order coherence time by more than a factor of four, photon bunching, and delayed emission pulses with Burnham-Chiao ringing behavior14 at high excitation d. These mesoscopically extended coherent states could be used to boost the performance of optoelectronic devices15 and enable entangled multi-photon quantum light sources16,17.
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    54. 54
      Baranov, D.; Toso, S.; Imran, M.; Manna, L. Investigation into the Photoluminescence Red Shift in Cesium Lead Bromide Nanocrystal Superlattices. J. Phys. Chem. Lett. 2019, 10, 655– 660,  DOI: 10.1021/acs.jpclett.9b00178
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      Investigation into the Photoluminescence Red Shift in Cesium Lead Bromide Nanocrystal Superlattices
      Baranov, Dmitry; Toso, Stefano; Imran, Muhammad; Manna, Liberato
      Journal of Physical Chemistry Letters (2019), 10 (3), 655-660CODEN: JPCLCD; ISSN:1948-7185. (American Chemical Society)
      The formation of cesium lead bromide (CsPbBr3) nanocrystal superlattices (NC SLs) is accompanied by a red shift in the NC photoluminescence (PL). The values of the PL red shift reported in the literature range from none to ∼100 meV without unifying explanation of the differences. Using a combination of confocal PL microcopy and steady-state optical spectroscopies we found that an overall PL red shift of ∼96 meV measured from a macroscopic sample of CsPbBr3 NC SLs has several contributions: ∼ 10-15 meV from a red shift in isolated and clean SLs, ∼ 30 meV from SLs with impurities of bulklike CsPbBr3 crystals on their surface, and up to 50 meV or more of the red shift coming from a photon propagation effect, specifically self-absorption. In addn., a self-assembly technique for growing micron-sized NC SLs on the surface of perfluorodecalin, an inert perfluorinated liq. and an antisolvent for NCs, is described.
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    55. 55
      Tong, Y.; Yao, E. P.; Manzi, A.; Bladt, E.; Wang, K.; Doblinger, M.; Bals, S.; Muller-Buschbaum, P.; Urban, A. S.; Polavarapu, L.; Feldmann, J. Spontaneous Self-Assembly of Perovskite Nanocrystals into Electronically Coupled Supercrystals: Toward Filling the Green Gap. Adv. Mater. 2018, 30, 1801117  DOI: 10.1002/adma.201801117
      There is no corresponding record for this reference.
    56. 56
      Imran, M.; Ijaz, P.; Baranov, D.; Goldoni, L.; Petralanda, U.; Akkerman, Q.; Abdelhady, A. L.; Prato, M.; Bianchini, P.; Infante, I.; Manna, L. Shape-Pure, Nearly Monodispersed CsPbBr3 Nanocubes Prepared Using Secondary Aliphatic Amines. Nano Lett. 2018, 18, 7822– 7831,  DOI: 10.1021/acs.nanolett.8b03598
      56
      Shape-Pure, Nearly Monodispersed CsPbBr3 Nanocubes Prepared Using Secondary Aliphatic Amines
      Imran, Muhammad; Ijaz, Palvasha; Baranov, Dmitry; Goldoni, Luca; Petralanda, Urko; Akkerman, Quinten; Abdelhady, Ahmed L.; Prato, Mirko; Bianchini, Paolo; Infante, Ivan; Manna, Liberato
      Nano Letters (2018), 18 (12), 7822-7831CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
      Fully inorg. Cs lead halide perovskite (CsPbX3) nanocrystals (NCs) were extensively studied due to their excellent optical properties, esp. their high photoluminescence quantum yield (PLQY) and the ease with which the PL can be tuned across the visible spectrum. So far, most strategies for synthesizing CsPbX3 NCs are highly sensitive to the processing conditions and ligand combinations. For example, in the synthesis of nanocubes of different sizes, it is not uncommon to have samples that contain various other shapes, such as nanoplatelets and nanosheets. Here, the authors report a new colloidal synthesis method for prepg. shape-pure and nearly monodispersed CsPbBr3 nanocubes using secondary amines. Regardless of the length of the alkyl chains, the oleic acid concn., and the reaction temp., only cube-shaped NCs were obtained. The shape purity and narrow size distribution of the nanocubes are evident from their sharp excitonic features and their ease of self-assembly in superlattices, reaching lateral dimensions of up to 50 μm. The authors attribute this excellent shape and phase purity to the inability of secondary amines to find the right steric conditions at the surface of the NCs, which consequently limits the formation of low-dimensional structures. Also, no contamination from other phases was obsd., not even from Cs4PbBr6, presumably due to the poor ability of secondary aliph. amines to coordinate to PbBr2 and, hence, to provide a reaction environment that is depleted in Pb.
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    57. 57
      Toso, S.; Baranov, D.; Giannini, C.; Marras, S.; Manna, L. Wide-Angle X-ray Diffraction Evidence of Structural Coherence in CsPbBr3 Nanocrystal Superlattices. ACS Mater. Lett. 2019, 1, 272– 276,  DOI: 10.1021/acsmaterialslett.9b00217
      57
      Wide-Angle X-ray Diffraction Evidence of Structural Coherence in CsPbBr3 Nanocrystal Superlattices
      Toso, Stefano; Baranov, Dmitry; Giannini, Cinzia; Marras, Sergio; Manna, Liberato
      ACS Materials Letters (2019), 1 (2), 272-276CODEN: AMLCEF; ISSN:2639-4979. (American Chemical Society)
      Films made of colloidal CsPbBr3 nanocrystals packed in isolated or densely-packed superlattices display a remarkably high degree of structural coherence. The structural coherence is revealed by the presence of satellite peaks accompanying Bragg reflections in wide-angle X-ray diffraction expts. in parallel-beam reflection geometry. The satellite peaks, also called "superlattice reflections", arise from the interference of X-rays diffracted by the at. planes of the orthorhombic perovskite lattice. The interference is due to the precise spatial periodicity of the nanocrystals sepd. by org. ligands in the superlattice. The presence of satellite peaks is a fingerprint of the high crystallinity and long-range order of nanocrystals, comparable to those of multilayer superlattices prepd. by phys. methods. The angular sepn. between satellite peaks is highly sensitive to changes in the superlattice periodicity. These characteristics of the satellite peaks are exploited to track the superlattice compression under vacuum, as well as to observe the superlattice growth in situ from colloidal solns. by slow solvent evapn.
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    58. 58
      Cherniukh, I.; Rainò, G.; Stöferle, T.; Burian, M.; Travesset, A.; Naumenko, D.; Amenitsch, H.; Erni, R.; Mahrt, R. F.; Bodnarchuk, M. I.; Kovalenko, M. V. Perovskite-Type Superlattices from Lead Halide Perovskite Nanocubes. Nature 2021, 593, 535– 542,  DOI: 10.1038/s41586-021-03492-5
      58
      Perovskite-type superlattices from lead halide perovskite nanocubes
      Cherniukh, Ihor; Raino, Gabriele; Stoferle, Thilo; Burian, Max; Travesset, Alex; Naumenko, Denys; Amenitsch, Heinz; Erni, Rolf; Mahrt, Rainer F.; Bodnarchuk, Maryna I.; Kovalenko, Maksym V.
      Nature (London, United Kingdom) (2021), 593 (7860), 535-542CODEN: NATUAS; ISSN:0028-0836. (Nature Portfolio)
      Perovskite-type (ABO3) binary and ternary nanocrystal superlattices, created via the shape-directed co-assembly of steric-stabilized, highly luminescent cubic CsPbBr3 nanocrystals (which occupy the B and/or O lattice sites), spherical Fe3O4 or NaGdF4 nanocrystals (A sites) and truncated-cuboid PbS nanocrystals (B sites), are presented. These ABO3 superlattices, as well as the binary NaCl and AlB2 superlattice structures that the authors demonstrate, exhibit a high degree of orientational ordering of the CsPbBr3 nanocubes. They also exhibit superfluorescence - a collective emission that results in a burst of photons with ultrafast radiative decay (22 ps) that could be tailored for use in ultrabright (quantum) light sources. The work paves the way for further exploration of complex, ordered and functionally useful perovskite mesostructures.
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    59. 59
      Cherniukh, I.; Raino, G.; Sekh, T. V.; Zhu, C.; Shynkarenko, Y.; John, R. A.; Kobiyama, E.; Mahrt, R. F.; Stoferle, T.; Erni, R.; Kovalenko, M. V.; Bodnarchuk, M. I. Shape-Directed Co-Assembly of Lead Halide Perovskite Nanocubes with Dielectric Nanodisks into Binary Nanocrystal Superlattices. ACS Nano 2021, 15, 16488– 16500,  DOI: 10.1021/acsnano.1c06047
      59
      Shape-Directed Co-Assembly of Lead Halide Perovskite Nanocubes with Dielectric Nanodisks into Binary Nanocrystal Superlattices
      Cherniukh, Ihor; Raino, Gabriele; Sekh, Taras V.; Zhu, Chenglian; Shynkarenko, Yevhen; John, Rohit Abraham; Kobiyama, Etsuki; Mahrt, Rainer F.; Stoferle, Thilo; Erni, Rolf; Kovalenko, Maksym V.; Bodnarchuk, Maryna I.
      ACS Nano (2021), 15 (10), 16488-16500CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
      Self-assembly of colloidal nanocrystals (NCs) holds great promise in the multiscale engineering of solid-state materials, whereby atomically engineered NC building blocks are arranged into long-range ordered structures-superlattices (SLs)-with synergistic phys. and chem. properties. Thus far, the reports have by far focused on single-component and binary systems of spherical NCs, yielding SLs isostructural with the known at. lattices. Far greater structural space, beyond the realm of known lattices, is anticipated from combining NCs of various shapes. Here, we report on the co-assembly of steric-stabilized CsPbBr3 nanocubes (5.3 nm) with disk-shaped LaF3 NCs (9.2-28.4 nm in diam., 1.6 nm in thickness) into binary SLs, yielding six columnar structures with AB, AB2, AB4, and AB6 stoichiometry, not obsd. before and in our ref. expts. with NC systems comprising spheres and disks. This striking effect of the cubic shape is rationalized herein using packing-d. calcns. Furthermore, in the systems with comparable dimensions of nanocubes (8.6 nm) and nanodisks (6.5 nm, 9.0 nm, 12.5 nm), other, noncolumnar structures are obsd., such as ReO3-type SL, featuring intimate intermixing and face-to-face alignment of disks and cubes, face-centered cubic or simple cubic sublattice of nanocubes, and two or three disks per one lattice site. Lamellar and ReO3-type SLs, employing large 8.6 nm CsPbBr3 NCs, exhibit characteristic features of the collective ultrafast light emission-superfluorescence-originating from the coherent coupling of emission dipoles in the excited state.
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    60. 60
      Bertolotti, F.; Nedelcu, G.; Vivani, A.; Cervellino, A.; Masciocchi, N.; Guagliardi, A.; Kovalenko, M. V. Crystal Structure, Morphology, and Surface Termination of Cyan-Emissive, Six-Monolayers-Thick CsPbBr3 Nanoplatelets from X-Ray Total Scattering. ACS Nano 2019, 13, 14294– 14307,  DOI: 10.1021/acsnano.9b07626
      60
      Crystal Structure, Morphology, and Surface Termination of Cyan-Emissive, Six-Monolayers-Thick CsPbBr3 Nanoplatelets from X-ray Total Scattering
      Bertolotti, Federica; Nedelcu, Georgian; Vivani, Anna; Cervellino, Antonio; Masciocchi, Norberto; Guagliardi, Antonietta; Kovalenko, Maksym V.
      ACS Nano (2019), 13 (12), 14294-14307CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
      Highly anisotropic colloidal CsPbBr3 nanoplatelets (NPLs) represent an appealing class of colloidal quantum wells with enhanced light emissivity. Strong quantum confinement imposed by the small platelet thickness and at. flatness gives rise to enhanced oscillator strength, higher exciton binding energy, and narrow emission linewidth. While discrete thicknesses manifest themselves in discrete bandgap energies, fine-tuning of the emission energy can be achieved by compositional modulations. Here we address one of the most debated aspects of perovskite nanoplatelets: their crystal structure. Starting with the direct imaging by high-resoln. electron microscopy (providing a clue on the pseudocubic faceting of the NPLs), we focus the study on X-ray total scattering techniques, based on the Debye scattering equation (DSE) approach, to obtain better atomistic insight. The nanoplatelets are six-monolayers thick and exhibit an orthorhombic structure. A thorough structure-morphol. characterization unveils a specific orientation of the axial and equatorial bromides of the PbBr6 octahedra vs. the NPLs thickness; we found that {010} and {101} planes of the orthorhombic CsPbBr3 lattice (Pnma space group) correspond to the six facets of the NPL, with basal planes being of {101} type. The NPLs undergo a lattice relaxation in comparison to cuboidal CsPbBr3 NCs; the major deformation is obsd. in the axial direction, which suggests a structural origin of the higher compliance along the b axis. The DSE-based anal. also supports a CsBr surface termination model, with half Cs sites and a half (or slightly more) Br sites vacant.
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    61. 61
      Dong, Y.; Qiao, T.; Kim, D.; Parobek, D.; Rossi, D.; Son, D. H. Precise Control of Quantum Confinement in Cesium Lead Halide Perovskite Quantum Dots via Thermodynamic Equilibrium. Nano Lett. 2018, 18, 3716– 3722,  DOI: 10.1021/acs.nanolett.8b00861
      61
      Precise Control of Quantum Confinement in Cesium Lead Halide Perovskite Quantum Dots via Thermodynamic Equilibrium
      Dong, Yitong; Qiao, Tian; Kim, Doyun; Parobek, David; Rossi, Daniel; Son, Dong Hee
      Nano Letters (2018), 18 (6), 3716-3722CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
      Cs lead halide (CsPbX3) nanocrystals have emerged as a new family of materials that can outperform the existing semiconductor nanocrystals due to their superb optical and charge-transport properties. However, the lack of a robust method for producing quantum dots with controlled size and high ensemble uniformity was 1 of the major obstacles in exploring the useful properties of excitons in zero-dimensional nanostructures of CsPbX3. Here, the authors report a new synthesis approach that enables the precise control of the size based on the equil. rather than kinetics, producing CsPbX3 quantum dots nearly free of heterogeneous broadening in their exciton luminescence. The high level of size control and ensemble uniformity achieved here will open the door to harnessing the benefits of excitons in CsPbX3 quantum dots for photonic and energy-harvesting applications.
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    62. 62
      Bodnarchuk, M. I.; Boehme, S. C.; Ten Brinck, S.; Bernasconi, C.; Shynkarenko, Y.; Krieg, F.; Widmer, R.; Aeschlimann, B.; Gunther, D.; Kovalenko, M. V.; Infante, I. Rationalizing and Controlling the Surface Structure and Electronic Passivation of Cesium Lead Halide Nanocrystals. ACS Energy Lett. 2019, 4, 63– 74,  DOI: 10.1021/acsenergylett.8b01669
      62
      Rationalizing and Controlling the Surface Structure and Electronic Passivation of Cesium Lead Halide Nanocrystals
      Bodnarchuk, Maryna I.; Boehme, Simon C.; ten Brinck, Stephanie; Bernasconi, Caterina; Shynkarenko, Yevhen; Krieg, Franziska; Widmer, Roland; Aeschlimann, Beat; Gunther, Detlef; Kovalenko, Maksym V.; Infante, Ivan
      ACS Energy Letters (2019), 4 (1), 63-74CODEN: AELCCP; ISSN:2380-8195. (American Chemical Society)
      Colloidal lead halide perovskite nanocrystals (NCs) have recently emerged as versatile photonic sources. Their processing and luminescent properties are challenged by the lability of their surfaces, i.e., the interface of the NC core and the ligand shell. On the example of CsPbBr3 NCs, we model the nanocrystal surface structure and its effect on the emergence of trap states using d. functional theory. We rationalize the typical observation of a degraded luminescence upon aging or the luminescence recovery upon postsynthesis surface treatments. The conclusions are corroborated by the elemental anal. We then propose a strategy for healing the surface trap states and for improving the colloidal stability by the combined treatment with didodecyldimethylammonium bromide and lead bromide and validate this approach exptl. This simple procedure results in robust colloids, which are highly pure and exhibit high photoluminescence quantum yields of up to 95-98%, retained even after three to four rounds of washing.
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    63. 63
      Park, J.; An, K.; Hwang, Y.; Park, J. G.; Noh, H. J.; Kim, J. Y.; Park, J. H.; Hwang, N. M.; Hyeon, T. Ultra-Large-Scale Syntheses of Monodisperse Nanocrystals. Nat. Mater. 2004, 3, 891– 895,  DOI: 10.1038/nmat1251
      63
      Ultra-large-scale syntheses of monodisperse nanocrystals
      Park, Jongnam; An, Kwangjin; Hwang, Yosun; Park, Je-Geun; Noh, Han-Jin; Kim, Jae-Young; Park, Jae-Hoon; Hwang, Nong-Moon; Hyeon, Taeghwan
      Nature Materials (2004), 3 (12), 891-895CODEN: NMAACR; ISSN:1476-1122. (Nature Publishing Group)
      The development of nanocrystals has been intensively pursued, not only for their fundamental scientific interest, but also for many technol. applications. The synthesis of monodisperse nanocrystals (size variation <5%) is of key importance, because the properties of these nanocrystals depend strongly on their dimensions. For example, the color sharpness of semiconductor nanocrystal-based optical devices is strongly dependent on the uniformity of the nanocrystals, and monodisperse magnetic nanocrystals are crit. for the next-generation multiterabit magnetic storage media. For these monodisperse nanocrystals to be used, an economical mass prodn. method needs to be developed. Unfortunately, however, in most syntheses reported so far, only subgram quantities of monodisperse nanocrystals were produced. Uniform-sized nanocrystals of CdSe and Au have been produced using colloidal chem. synthetic procedures. In addn., monodisperse magnetic nanocrystals such as Fe, Co, γ-Fe2O3, and Fe3O4 have been synthesized by using various synthetic methods. Here, we report on the ultralarge-scale synthesis of monodisperse nanocrystals using inexpensive and nontoxic metal salts as reactants. We were able to synthesize as much as 40 g of monodisperse nanocrystals in a single reaction, without a size sorting process. Moreover, the particle size could be controlled simply by varying the exptl. conditions. The current synthetic procedure is very general and nanocrystals of many transition metal oxides were successfully synthesized using a very similar procedure.
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    64. 64
      Travesset, A. Topological Structure Prediction in Binary Nanoparticle Superlattices. Soft Matter 2017, 13, 147– 157,  DOI: 10.1039/C6SM00713A
      64
      Topological structure prediction in binary nanoparticle superlattices
      Travesset, A.
      Soft Matter (2017), 13 (1), 147-157CODEN: SMOABF; ISSN:1744-683X. (Royal Society of Chemistry)
      Systems of spherical nanoparticles with capping ligands have been shown to self-assemble into beautiful superlattices of fascinating structure and complexity. In this paper, I show that the spherical geometry of the nanoparticle imposes constraints on the nature of the topol. defects assocd. with the capping ligand and that such topol. defects control the structure and stability of the superlattices that can be assembled. All these considerations form the basis for the orbifold topol. model (OTM) described in this paper. The model quant. predicts the structure of super-lattices where capping ligands are hydrocarbon chains in excellent agreement with exptl. results, explains the appearance of low packing fraction lattices as equil., why certain similar structures are more stable (bccAB6vs. CaB6, AuCu vs. CsCl, etc.) and many other exptl. observations.
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    65. 65
      Boles, M. A.; Talapin, D. V. Binary Assembly of PbS and Au Nanocrystals: Patchy PbS Surface Ligand Coverage Stabilizes the CuAu Superlattice. ACS Nano 2019, 13, 5375– 5384,  DOI: 10.1021/acsnano.9b00006
      65
      Binary Assembly of PbS and Au Nanocrystals: Patchy PbS Surface Ligand Coverage Stabilizes the CuAu Superlattice
      Boles, Michael A.; Talapin, Dmitri V.
      ACS Nano (2019), 13 (5), 5375-5384CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
      Self-assembly of two sizes of nearly spherical colloidal nanocrystals (NCs) capped with hydrocarbon surface ligands has been shown to produce more than 20 distinct phases of binary nanocrystal superlattices (BNSLs). Such structural diversity, in striking contrast to binary systems of micron-sized colloidal beads, cannot be rationalized by models assuming entropy-driven crystn. of simple spheres. In this work, we show that the PbS ligand binding equil. controls the relative stability of two closely related BNSL structures featuring alternating layers of PbS and Au NCs. At an intermediate size ratio, as-prepd. PbS NCs assemble with Au NCs into CuAu BNSLs featuring orientational coherence of PbS NCs across the lattice. Measurement of interparticle sepns. within CuAu and modeling of the structure reveal that PbS inorg. cores are nearly in contact through (100) NC surfaces in the square tiling of the CuAu basal plane. On the other hand, AlB2 BNSLs with PbS NCs packed in random orientations were found to be the dominant self-assembly product when the same binary NC soln. was evapd. in the presence of added oleic acid (OAH). Soln. NMR titrn. expts. confirmed that added OAH binds to PbS NCs, implicating ligand surface coverage as an important factor influencing the relative stability of CuAu and AlB2 BNSLs at the exptl. size ratio. From these results, we conclude that as-prepd. PbS NCs feature sparsely covered (100) surfaces and thus effectively flat patches along NC x-, y-, and z-directions. Such anisotropic PbS-PbS interactions can be efficiently screened by restoring effectively spherical NC shape via addn. of OAH to the binary assembly soln. Our findings underscore the important contribution of NC surfaces to superlattice phase stability and offer a strategy for targeted BNSL assembly.
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    66. 66
      Zhuang, J.; Wu, H.; Yang, Y.; Cao, Y. C. Supercrystalline Colloidal Particles from Artificial Atoms. J. Am. Chem. Soc. 2007, 129, 14166– 14167,  DOI: 10.1021/ja076494i
      66
      Supercrystalline colloidal particles from artificial atoms
      Zhuang, Jiaqi; Wu, Huimeng; Yang, Yongan; Cao, Y. Charles
      Journal of the American Chemical Society (2007), 129 (46), 14166-14167CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
      In this paper, we report an approach for using solvophobic interactions to synthesize well-defined colloidal superparticles from nonpolar-solvent-dispersible Fe3O4 nanoparticle artificial atoms. These colloidal superparticles possess a "single-supercrystal" structure, of which Fe3O4 artificial atoms occupy the lattice points of a face-centered cubic superlattice. In addn., these superparticles exhibit superlattice fringes under a low-resoln. TEM, providing an interesting analog to the lattice fringes of colloidal nanocrystals under a high-resoln. TEM. Moreover, these superparticles can be further assembled into close-packed solid structures, demonstrating their role as a new type of building block in nanoscience.
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    67. 67
      Zhuang, J.; Wu, H.; Yang, Y.; Cao, Y. C. Controlling Colloidal Superparticle Growth through Solvophobic Interactions. Angew. Chem., Int. Ed. 2008, 47, 2208– 2212,  DOI: 10.1002/anie.200705049
      67
      Controlling colloidal superparticle growth through solvophobic interactions
      Zhuang, Jiaqi; Wu, Huimeng; Yang, Yongan; Cao, Y. Charles
      Angewandte Chemie, International Edition (2008), 47 (12), 2208-2212CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
      A supramol. chem. approach is used to make supercryst. spherical colloidal superparticles from nanoparticles. Detailed mechanistic studies show that the formation of the SPs is a two-step process. The major driving force for superparticle formation is the solvophobic interaction between nanoparticle building blocks and the growth soln.; fine-tuning the interaction led to a size-controlled synthesis.
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    68. 68
      Yang, Y.; Wang, B.; Shen, X.; Yao, L.; Wang, L.; Chen, X.; Xie, S.; Li, T.; Hu, J.; Yang, D.; Dong, A. Scalable Assembly of Crystalline Binary Nanocrystal Superparticles and Their Enhanced Magnetic and Electrochemical Properties. J. Am. Chem. Soc. 2018, 140, 15038– 15047,  DOI: 10.1021/jacs.8b09779
      68
      Scalable Assembly of Crystalline Binary Nanocrystal Superparticles and Their Enhanced Magnetic and Electrochemical Properties
      Yang, Yuchi; Wang, Biwei; Shen, Xiudi; Yao, Luyin; Wang, Lei; Chen, Xiao; Xie, Songhai; Li, Tongtao; Hu, Jianhua; Yang, Dong; Dong, Angang
      Journal of the American Chemical Society (2018), 140 (44), 15038-15047CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
      Self-assembled binary nanocrystal superlattices (BNSLs) represent an important class of solid-state materials with potentially designed properties. In pursuit of widening the range of applications for binary superlattice materials, it is desirable to develop scalable assembly methods that enable high-quality BNSLs with tailored compns., structures, and morphologies. We report the gram-scale assembly of cryst. binary nanocrystal superparticles with high phase purity through an emulsion-based process. The structure of the resulting BNSL colloids can be tuned in a wide range (AB13, AlB2, MgZn2, NaCl, and CaCu5) by varying the size and(or) no. ratios of the 2 nanocrystal components. Access to large-scale, phase-pure BNSL colloids offers vast opportunities for investigating their physiochem. properties, as exemplified by AB13-type CoFe2O4-Fe3O4 binary superparticles. CoFe2O4-Fe3O4 binary superparticles not only display enhanced magnetic coupling but also exhibit superior lithium-storage properties. The nonclosed-packed NC packing arrangements of AB13-type binary superparticles are found to play a key role in facilitating lithiation/delithiation kinetics and maintaining structural integrity during repeated cycling. Our work establishes the scalable assembly of high-quality BNSL colloids, which is beneficial for accelerating the exploration of multicomponent nanocrystal superlattices toward various applications.
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    69. 69
      Kister, T.; Mravlak, M.; Schilling, T.; Kraus, T. Pressure-Controlled Formation of Crystalline, Janus, and Core-Shell Supraparticles. Nanoscale 2016, 8, 13377– 13384,  DOI: 10.1039/C6NR01940D
      69
      Pressure-controlled formation of crystalline, Janus, and core-shell supraparticles
      Kister, Thomas; Mravlak, Marko; Schilling, Tanja; Kraus, Tobias
      Nanoscale (2016), 8 (27), 13377-13384CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)
      Binary mixts. of nanoparticles self-assemble in the confinement of evapg. oil droplets and form regular supraparticles. We demonstrate that moderate pressure differences on the order of 100 kPa change the particles' self-assembly behavior. Cryst. superlattices, Janus particles, and core-shell particle arrangements form in the same dispersions when changing the working pressure or the surfactant that sets the Laplace pressure inside the droplets. Mol. dynamics simulations confirm that pressure-dependent interparticle potentials affect the self-assembly route of the confined particles. Optical spectrometry, small-angle X-ray scattering and electron microscopy are used to compare expts. and simulations and confirm that the onset of self-assembly depends on particle size and pressure. The overall formation mechanism reminds of the demixing of binary alloys with different phase diagrams.
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    70. 70
      Tang, Y.; Gomez, L.; Lesage, A.; Marino, E.; Kodger, T. E.; Meijer, J. M.; Kolpakov, P.; Meng, J.; Zheng, K.; Gregorkiewicz, T.; Schall, P. Highly Stable Perovskite Supercrystals via Oil-in-Oil Templating. Nano Lett. 2020, 20, 5997– 6004,  DOI: 10.1021/acs.nanolett.0c02005
      70
      Highly Stable Perovskite Supercrystals via Oil-in-Oil Templating
      Tang, Yingying; Gomez, Leyre; Lesage, Arnon; Marino, Emanuele; Kodger, Thomas E.; Meijer, Janne-Mieke; Kolpakov, Paul; Meng, Jie; Zheng, Kaibo; Gregorkiewicz, Tom; Schall, Peter
      Nano Letters (2020), 20 (8), 5997-6004CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
      The large-scale assembly control of spherical, cubic, and hexagonal supercrystals (SCs) of inorg. perovskite nanocrystals (NCs) through templating by oil-in-oil emulsions is reported. An interplay between the roundness of the cubic NCs and the tension of the confining droplet surface sets the superstructure morphol., and this interplay is exploited to design dense hyperlattices of SCs. The SC films show strongly enhanced stability for ≥2 mo without obvious structural degrdn. and minor optical changes. The results on the controlled large-scale assembly of perovskite NC superstructures provide new prospects for the bottom-up prodn. of optoelectronic devices based on the microfluidic prodn. of mesoscopic building blocks.
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    71. 71
      Wang, D.; van der Wee, E. B.; Zanaga, D.; Altantzis, T.; Wu, Y.; Dasgupta, T.; Dijkstra, M.; Murray, C. B.; Bals, S.; van Blaaderen, A. Quantitative 3D Real-Space Analysis of Laves Phase Supraparticles. Nat. Commun. 2021, 12, 3980,  DOI: 10.1038/s41467-021-24227-0
      71
      Quantitative 3D real-space analysis of Laves phase supraparticles
      Wang, Da; van der Wee, Ernest B.; Zanaga, Daniele; Altantzis, Thomas; Wu, Yaoting; Dasgupta, Tonnishtha; Dijkstra, Marjolein; Murray, Christopher B.; Bals, Sara; van Blaaderen, Alfons
      Nature Communications (2021), 12 (1), 3980CODEN: NCAOBW; ISSN:2041-1723. (Nature Research)
      Assembling binary mixts. of nanoparticles into crystals, gives rise to collective properties depending on the crystal structure and the individual properties of both species. However, quant. 3D real-space anal. of binary colloidal crystals with a thickness of more than 10 layers of particles has rarely been performed. Here we demonstrate that an excess of one species in the binary nanoparticle mixt. suppresses the formation of icosahedral order in the self-assembly in droplets, allowing the study of bulk-like binary crystal structures with a spherical morphol. also called supraparticles. As example of the approach, we show single-particle level anal. of over 50 layers of Laves phase binary crystals of hard-sphere-like nanoparticles using electron tomog. We observe a cryst. lattice composed of a random mixt. of the Laves phases. The no. ratio of the binary species in the crystal lattice matches that of a perfect Laves crystal. Our methodol. can be applied to study the structure of a broad range of binary crystals, giving insights into the structure formation mechanisms and structure-property relations of nanomaterials.
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      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhsFOgtLjJ&md5=21bfca72218ab37ee862c372d278d16c
    72. 72
      Montanarella, F.; Geuchies, J. J.; Dasgupta, T.; Prins, P. T.; van Overbeek, C.; Dattani, R.; Baesjou, P.; Dijkstra, M.; Petukhov, A. V.; van Blaaderen, A.; Vanmaekelbergh, D. Crystallization of Nanocrystals in Spherical Confinement Probed by in Situ X-ray Scattering. Nano Lett. 2018, 18, 3675– 3681,  DOI: 10.1021/acs.nanolett.8b00809
      72
      Crystallization of Nanocrystals in Spherical Confinement Probed by in Situ X-ray Scattering
      Montanarella, Federico; Geuchies, Jaco J.; Dasgupta, Tonnishtha; Prins, P. Tim; van Overbeek, Carlo; Dattani, Rajeev; Baesjou, Patrick; Dijkstra, Marjolein; Petukhov, Andrei V.; van Blaaderen, Alfons; Vanmaekelbergh, Daniel
      Nano Letters (2018), 18 (6), 3675-3681CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
      The formation of supraparticles from nanocrystals confined in slowly evapg. oil droplets in an oil-in-H2O emulsion was studied. The nanocrystals consist of an FeO core, a CoFe2O4 shell, and oleate capping ligands, with an overall diam. of 12.5 nm. In situ small- and wide-angle x-ray scattering expts. were performed during the entire period of solvent evapn. and colloidal crystn. A slow increase in the vol. fraction of nanocrystals inside the oil droplets up to 20%, at which a sudden crystn. occurs was obsd. The computer simulations show that crystn. at such a low vol. fraction is only possible if attractive interactions between colloidal nanocrystals are taken into account in the model as well. The spherical supraparticles have a diam. of ∼700 nm and consist of a few cryst. fcc. domains. Nanocrystal supraparticles bear importance for magnetic and optoelectronic applications, such as color tunable biolabels, color tunable phosphors in LEDs, and miniaturized lasers.
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    73. 73
      Becker, M. A.; Vaxenburg, R.; Nedelcu, G.; Sercel, P. C.; Shabaev, A.; Mehl, M. J.; Michopoulos, J. G.; Lambrakos, S. G.; Bernstein, N.; Lyons, J. L.; Stöferle, T.; Mahrt, R. F.; Kovalenko, M. V.; Norris, D. J.; Rainò, G.; Efros, A. L. Bright Triplet Excitons in Caesium Lead Halide Perovskites. Nature 2018, 553, 189– 193,  DOI: 10.1038/nature25147
      73
      Bright triplet excitons in caesium lead halide perovskites
      Becker, Michael A.; Vaxenburg, Roman; Nedelcu, Georgian; Sercel, Peter C.; Shabaev, Andrew; Mehl, Michael J.; Michopoulos, John G.; Lambrakos, Samuel G.; Bernstein, Noam; Lyons, John L.; Stoferle, Thilo; Mahrt, Rainer F.; Kovalenko, Maksym V.; Norris, David J.; Raino, Gabriele; Efros, Alexander L.
      Nature (London, United Kingdom) (2018), 553 (7687), 189-193CODEN: NATUAS; ISSN:0028-0836. (Nature Research)
      Nanostructured semiconductors emit light from electronic states known as excitons. For org. materials, Hund's rules state that the lowest-energy exciton is a poorly emitting triplet state. For inorg. semiconductors, similar rules predict an analog of this triplet state known as the 'dark exciton'. Because dark excitons release photons slowly, hindering emission from inorg. nanostructures, materials that disobey these rules have been sought. However, despite considerable exptl. and theor. efforts, no inorg. semiconductors have been identified in which the lowest exciton is bright. Here we show that the lowest exciton in caesium lead halide perovskites (CsPbX3, with X = Cl, Br or I) involves a highly emissive triplet state. We first use an effective-mass model and group theory to demonstrate the possibility of such a state existing, which can occur when the strong spin-orbit coupling in the conduction band of a perovskite is combined with the Rashba effect. We then apply our model to CsPbX3 nanocrystals, and measure size- and compn.-dependent fluorescence at the single-nanocrystal level. The bright triplet character of the lowest exciton explains the anomalous photon-emission rates of these materials, which emit about 20 and 1,000 times faster than any other semiconductor nanocrystal at room and cryogenic temps., resp. The existence of this bright triplet exciton is further confirmed by anal. of the fine structure in low-temp. fluorescence spectra. For semiconductor nanocrystals, which are already used in lighting, lasers and displays, these excitons could lead to materials with brighter emission. More generally, our results provide criteria for identifying other semiconductors that exhibit bright excitons, with potential implications for optoelectronic devices.
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    74. 74
      Becker, M. A.; Scarpelli, L.; Nedelcu, G.; Raino, G.; Masia, F.; Borri, P.; Stoferle, T.; Kovalenko, M. V.; Langbein, W.; Mahrt, R. F. Long Exciton Dephasing Time and Coherent Phonon Coupling in CsPbBr2Cl Perovskite Nanocrystals. Nano Lett. 2018, 18, 7546– 7551,  DOI: 10.1021/acs.nanolett.8b03027
      74
      Long Exciton Dephasing Time and Coherent Phonon Coupling in CsPbBr2Cl Perovskite Nanocrystals
      Becker, Michael A.; Scarpelli, Lorenzo; Nedelcu, Georgian; Raino, Gabriele; Masia, Francesco; Borri, Paola; Stoferle, Thilo; Kovalenko, Maksym V.; Langbein, Wolfgang; Mahrt, Rainer F.
      Nano Letters (2018), 18 (12), 7546-7551CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)
      Fully inorg. cesium lead halide perovskite nanocrystals (NCs) have shown to exhibit outstanding optical properties such as wide spectral tunability, high quantum yield, high oscillator strength as well as blinking-free single photon emission, and low spectral diffusion. Here, we report measurements of the coherent and incoherent exciton dynamics on the 100 fs to 10 ns time scale, detg. dephasing and d. decay rates in these NCs. The expts. are performed on CsPbBr2Cl NCs using transient resonant three-pulse four-wave mixing (FWM) in heterodyne detection at temps. ranging from 5 to 50 K. We found a low-temp. exciton dephasing time of 24.5 ± 1.0 ps, inferred from the decay of the photon-echo amplitude at 5 K, corresponding to a homogeneous line width (fwhm) of 54 ± 5 μeV. Furthermore, oscillations in the photon-echo signal on a picosecond time scale are obsd. and attributed to coherent coupling of the exciton to a quantized phonon mode with 3.45 meV energy.
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    75. 75
      Hestand, N. J.; Spano, F. C. Expanded Theory of H- and J-Molecular Aggregates: The Effects of Vibronic Coupling and Intermolecular Charge Transfer. Chem. Rev. 2018, 118, 7069– 7163,  DOI: 10.1021/acs.chemrev.7b00581
      75
      Expanded Theory of H- and J-Molecular Aggregates: Effects of Vibronic Coupling and Intermolecular Charge Transfer
      Hestand, Nicholas J.; Spano, Frank C.
      Chemical Reviews (Washington, DC, United States) (2018), 118 (15), 7069-7163CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
      A review. The electronic excited states of mol. aggregates and their photophys. signatures have long fascinated spectroscopists and theoreticians alike since the advent of Frenkel exciton theory almost 90 years ago. The influence of mol. packing on basic optical probes like absorption and photoluminescence was originally worked out by Kasha for aggregates dominated by Coulombic intermol. interactions, eventually leading to the classification of J- and H-aggregates. This review outlines advances made in understanding the relationship between aggregate structure and photophysics when vibronic coupling and intermol. charge transfer are incorporated. An assortment of packing geometries is considered from the humble mol. dimer to more exotic structures including linear and bent aggregates, two-dimensional herringbone and "HJ" aggregates, and chiral aggregates. The interplay between long-range Coulomb coupling and short-range charge-transfer-mediated coupling strongly depends on the aggregate architecture leading to a wide array of photophys. behaviors.
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    76. 76
      Yaffe, O.; Guo, Y.; Tan, L. Z.; Egger, D. A.; Hull, T.; Stoumpos, C. C.; Zheng, F.; Heinz, T. F.; Kronik, L.; Kanatzidis, M. G.; Owen, J. S.; Rappe, A. M.; Pimenta, M. A.; Brus, L. E. Local Polar Fluctuations in Lead Halide Perovskite Crystals. Phys. Rev. Lett. 2017, 118, 136001,  DOI: 10.1103/PhysRevLett.118.136001
      76
      Local polar fluctuations in lead halide perovskite crystals
      Yaffe, Omer; Guo, Yinsheng; Tan, Liang Z.; Egger, David A.; Hull, Trevor; Stoumpos, Constantinos C.; Zheng, Fan; Heinz, Tony F.; Kronik, Leeor; Kanatzidis, Mercouri G.; Owen, Jonathan S.; Rappe, Andrew M.; Pimenta, Marcos A.; Brus, Louis E.
      Physical Review Letters (2017), 118 (13), 136001/1-136001/6CODEN: PRLTAO; ISSN:1079-7114. (American Physical Society)
      Hybrid lead-halide perovskites have emerged as an excellent class of photovoltaic materials. Recent reports suggest that the org. mol. cation is responsible for local polar fluctuations that inhibit carrier recombination. We combine low-frequency Raman scattering with first-principles mol. dynamics (MD) to study the fundamental nature of these local polar fluctuations. Our observations of a strong central peak in the cubic phase of both hybrid (CH3NH3PbBr3) and all-inorg. (CsPbBr3) leadhalide perovskites show that anharmonic, local polar fluctuations are intrinsic to the general lead-halide perovskite structure, and not unique to the dipolar org. cation. MD simulations indicate that head-tohead Cs motion coupled to Br face expansion, occurring on a few hundred femtosecond time scale, drives the local polar fluctuations in CsPbBr3.
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    77. 77
      Lanigan-Atkins, T.; He, X.; Krogstad, M. J.; Pajerowski, D. M.; Abernathy, D. L.; Xu, G.; Xu, Z.; Chung, D. Y.; Kanatzidis, M. G.; Rosenkranz, S.; Osborn, R.; Delaire, O. Two-Dimensional Overdamped Fluctuations of the Soft Perovskite Lattice in CsPbBr3. Nat. Mater. 2021, 20, 977– 983,  DOI: 10.1038/s41563-021-00947-y
      77
      Two-dimensional overdamped fluctuations of the soft perovskite lattice in CsPbBr3
      Lanigan-Atkins, T.; He, X.; Krogstad, M. J.; Pajerowski, D. M.; Abernathy, D. L.; Xu, Guangyong N. M. N.; Xu, Zhijun; Chung, D.-Y.; Kanatzidis, M. G.; Rosenkranz, S.; Osborn, R.; Delaire, O.
      Nature Materials (2021), 20 (7), 977-983CODEN: NMAACR; ISSN:1476-1122. (Nature Portfolio)
      Lead halide perovskites exhibit structural instabilities and large at. fluctuations thought to impact their optical and thermal properties, yet detailed structural and temporal correlations of their at. motions remain poorly understood. Here, these correlations are resolved in CsPbBr3 crystals using momentum-resolved neutron and X-ray scattering measurements as a function of temp., complemented with first-principles simulations. We uncover a striking network of diffuse scattering rods, arising from the liq.-like damping of low-energy Br-dominated phonons, reproduced in our simulations of the anharmonic phonon self-energy. These overdamped modes cover a continuum of wave vectors along the edges of the cubic Brillouin zone, corresponding to two-dimensional sheets of correlated rotations in real space, and could represent precursors to proposed two-dimensional polarons. Further, these motions directly impact the electronic gap edge states, linking soft anharmonic lattice dynamics and optoelectronic properties. These results provide insights into the highly unusual at. dynamics of halide perovskites, relevant to further optimization of their optical and thermal properties.
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    78. 78
      Baranov, D.; Fieramosca, A.; Yang, R. X.; Polimeno, L.; Lerario, G.; Toso, S.; Giansante, C.; Giorgi, M.; Tan, L. Z.; Sanvitto, D.; Manna, L. Aging of Self-Assembled Lead Halide Perovskite Nanocrystal Superlattices: Effects on Photoluminescence and Energy Transfer. ACS Nano 2021, 15, 650– 664,  DOI: 10.1021/acsnano.0c06595
      78
      Aging of Self-Assembled Lead Halide Perovskite Nanocrystal Superlattices: Effects on Photoluminescence and Energy Transfer
      Baranov, Dmitry; Fieramosca, Antonio; Yang, Ruo Xi; Polimeno, Laura; Lerario, Giovanni; Toso, Stefano; Giansante, Carlo; Giorgi, Milena De; Tan, Liang Z.; Sanvitto, Daniele; Manna, Liberato
      ACS Nano (2021), 15 (1), 650-664CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
      Excitonic coupling, electronic coupling, and cooperative interactions in self-assembled lead halide perovskite nanocrystals were reported to give rise to a red-shifted collective emission peak with accelerated dynamics. Here, we report that similar spectroscopic features could appear as a result of the nanocrystal reactivity within the self-assembled superlattices. This is demonstrated by studying CsPbBr3 nanocrystal superlattices over time with room-temp. and cryogenic micro-photoluminescence spectroscopy, X-ray diffraction, and electron microscopy. It is shown that a gradual contraction of the superlattices and subsequent coalescence of the nanocrystals occurs over several days of keeping such structures under vacuum. As a result, a narrow, low-energy emission peak is obsd. at 4 K with a concomitant shortening of the photoluminescence lifetime due to the energy transfer between nanocrystals. When exposed to air, self-assembled CsPbBr3 nanocrystals develop bulk-like CsPbBr3 particles on top of the superlattices. At 4 K, these particles produce a distribution of narrow, low-energy emission peaks with short lifetimes and excitation fluence-dependent, oscillatory decays. Overall, the aging of CsPbBr3 nanocrystal assemblies dramatically alters their emission properties and that should not be overlooked when studying collective optoelectronic phenomena nor confused with superfluorescence effects.
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    79. 79
      De Roo, J.; Ibanez, M.; Geiregat, P.; Nedelcu, G.; Walravens, W.; Maes, J.; Martins, J. C.; Van Driessche, I.; Kovalenko, M. V.; Hens, Z. Highly Dynamic Ligand Binding and Light Absorption Coefficient of Cesium Lead Bromide Perovskite Nanocrystals. ACS Nano 2016, 10, 2071– 2081,  DOI: 10.1021/acsnano.5b06295
      79
      Highly Dynamic Ligand Binding and Light Absorption Coefficient of Cesium Lead Bromide Perovskite Nanocrystals
      De Roo, Jonathan; Ibanez, Maria; Geiregat, Pieter; Nedelcu, Georgian; Walravens, Willem; Maes, Jorick; Martins, Jose C.; Van Driessche, Isabel; Kovalenko, Maksym V.; Hens, Zeger
      ACS Nano (2016), 10 (2), 2071-2081CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
      Lead halide perovskite materials have attracted significant attention in the context of photovoltaics and other optoelectronic applications, and recently, research efforts have been directed to nanostructured lead halide perovskites. Collodial nanocrystals (NCs) of cesium lead halides (CsPbX3, X = Cl, Br, I) exhibit bright photoluminescence, with emission tunable over the entire visible spectral region. However, previous studies on CsPbX3 NCs did not address key aspects of their chem. and photophysics such as surface chem. and quant. light absorption. Here, we elaborate on the synthesis of CsPbBr3 NCs and their surface chem. In addn., the intrinsic absorption coeff. was detd. exptl. by combining elemental anal. with accurate optical absorption measurements. 1H soln. NMR spectroscopy was used to characterize sample purity, elucidate the surface chem., and evaluate the influence of purifn. methods on the surface compn. We find that ligand binding to the NC surface is highly dynamic, and therefore, ligands are easily lost during the isolation and purifn. procedures. However, when a small amt. of both oleic acid and oleylamine is added, the NCs can be purified, maintaining optical, colloidal, and material integrity. In addn., we find that a high amine content in the ligand shell increases the quantum yield due to the improved binding of the carboxylic acid.
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    80. 80
      Ibanez, M.; Korkosz, R. J.; Luo, Z.; Riba, P.; Cadavid, D.; Ortega, S.; Cabot, A.; Kanatzidis, M. G. Electron Doping in Bottom-Up Engineered Thermoelectric Nanomaterials through HCl-Mediated Ligand Displacement. J. Am. Chem. Soc. 2015, 137, 4046– 4049,  DOI: 10.1021/jacs.5b00091
      80
      Electron Doping in Bottom-Up Engineered Thermoelectric Nanomaterials through HCl-Mediated Ligand Displacement
      Ibanez, Maria; Korkosz, Rachel J.; Luo, Zhishan; Riba, Pau; Cadavid, Doris; Ortega, Silvia; Cabot, Andreu; Kanatzidis, Mercouri G.
      Journal of the American Chemical Society (2015), 137 (12), 4046-4049CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
      A simple and effective method to introduce precise amts. of doping in nanomaterials produced from the bottom-up assembly of colloidal nanoparticles (NPs) is described. The procedure takes advantage of a ligand displacement step to incorporate controlled concns. of halide ions while removing carboxylic acids from the NP surface. Upon consolidation of the NPs into dense pellets, halide ions diffuse within the crystal structure, doping the anion sublattice and achieving n-type elec. doping. Through the characterization of the thermoelec. properties of nanocryst. PbS, the authors demonstrate this strategy to be effective to control charge transport properties on thermoelec. nanomaterials assembled from NP building blocks. This approach is subsequently extended to PbTexSe1-x@PbS core-shell NPs, where a significant enhancement of the thermoelec. figure of merit is achieved.
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    81. 81
      Kremer, J. R.; Mastronarde, D. N.; McIntosh, J. R. Computer Visualization of Three-Dimensional Image Data Using IMOD. J. Struct. Biol. 1996, 116, 71– 76,  DOI: 10.1006/jsbi.1996.0013
      81
      Computer visualization of three-dimensional image data using IMOD
      Kremer J R; Mastronarde D N; McIntosh J R
      Journal of structural biology (1996), 116 (1), 71-6 ISSN:1047-8477.
      We have developed a computer software package, IMOD, as a tool for analyzing and viewing three-dimensional biological image data. IMOD is useful for studying and modeling data from tomographic, serial section, and optical section reconstructions. The software allows image data to be visualized by several different methods. Models of the image data can be visualized by volume or contour surface rendering and can yield quantitative information.
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    82. 82
      Amenitsch, H.; Bernstorff, S.; Laggner, P. High-Flux Beamline for Small-Angle X-Ray Scattering at ELETTRA. Rev. Sci. Instrum. 1995, 66, 1624– 1626,  DOI: 10.1063/1.1145864
      82
      High-flux beamline for small-angle x-ray scattering at ELETTRA
      Amenitsch, H.; Bernstorff, S.; Laggner, P.
      Review of Scientific Instruments (1995), 66 (2, Pt. 2), 1624-6CODEN: RSINAK; ISSN:0034-6748. (American Institute of Physics)
      The optical layout and the expected performance of the new high-flux SAXS beamline at ELETTRA is presented. From the high-power wiggler spectrum the 3 discrete energies 5.4, 8, and 16 keV will be selected with a double-crystal monochromator which contains 3 pairs of sepd. asym. cut plane Si(111) crystals. Downstream, the beam will be focused by a torodial mirror. The optical axis of the beamline will be horizontally 1.25 mrad off wiggler axis and the beamline will accept ∼1 mrad horizontally and 0.3 mrad vertically. The beamline will operate with a SAXS resoln. between 10 and a least 1000 Å in d spacing at 8 keV and was optimized with respect to extreme flux. A flux at the sample in the order of 1013 ph/s is expected for 8 keV photons (2 GeV, 400 mA). It will be possible to perform wide angle scattering measurements in the range of 3.5 and 7 Å d spacing at 8 keV simultaneously.
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    83. 83
      Ilavsky, J. Nika: Software for Two-Dimensional Data Reduction. J. Appl. Crystallogr. 2012, 45, 324– 328,  DOI: 10.1107/S0021889812004037
      83
      Nika: software for two-dimensional data reduction
      Ilavsky, Jan
      Journal of Applied Crystallography (2012), 45 (2), 324-328CODEN: JACGAR; ISSN:0021-8898. (International Union of Crystallography)
      Nika is an Igor Pro-based package for correction, calibration and redn. of two-dimensional area-detector data into one-dimensional data ('lineouts'). It is free (although the user needs a paid license for Igor Pro), open source and highly flexible. While typically used for small-angle X-ray scattering (SAXS) data, it can also be used for grazing-incidence SAXS data, wide-angle diffraction data and even small-angle neutron scattering data. It has been widely available to the user community since about 2005, and it is currently used at the SAXS instruments of selected large-scale facilities as their main data redn. package. It is, however, also suitable for desktop instruments when the manufacturer's software is not available or appropriate. Since it is distributed as source code, it can be scrutinized, verified and modified by users to suit their needs.
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    84. 84
      Jiang, Z. GIXSGUI: a MATLAB Toolbox for Grazing-Incidence X-ray Scattering Data Visualization and Reduction, and Indexing of Buried Three-Dimensional Periodic Nanostructured Films. J. Appl. Crystallogr. 2015, 48, 917– 926,  DOI: 10.1107/S1600576715004434
      84
      GIXSGUI: a MATLAB toolbox for grazing-incidence X-ray scattering data visualization and reduction, and indexing of buried three-dimensional periodic nanostructured films
      Jiang, Zhang
      Journal of Applied Crystallography (2015), 48 (3), 917-926CODEN: JACGAR; ISSN:1600-5767. (International Union of Crystallography)
      GIXSGUI is a MATLAB toolbox that offers both a graphical user interface and script-based access to visualize and process grazing-incidence X-ray scattering data from nanostructures on surfaces and in thin films. It provides routine surface scattering data redn. methods such as geometric correction, one-dimensional intensity linecut, two-dimensional intensity reshaping etc. Three-dimensional indexing is also implemented to det. the space group and lattice parameters of buried organized nanoscopic structures in supported thin films.
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  • Supporting Information

    Supporting Information

    including three Supplementary Video files. The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsnano.1c10702.

    • Video S1: Tomographic reconstruction of binary AlB2-type SL comprising 5.3 nm CsPbBr3 nanocubes and 15.2 nm NaGdF4 spherical NCs (AVI)

    • Video S2: Tomographic reconstruction of binary CaC2-type SL comprising 8.6 nm CsPbBr3 nanocubes and 31.5 nm NaGdF4 thick nanodisks (AVI)

    • GISAXS characterization of AlB2-type SL; packing analysis of AlB2-, AB2- and b-ABO6-type SLs; additional TEM characterization of NC building blocks and binary NC SLs (PDF)

    • Video S3: Tomographic reconstruction of binary ABO3-type supraparticle comprising 8.6 nm CsPbBr3 nanocubes and 18.6 nm NaGdF4 spherical NCs (AVI)


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